# Adafruit Circuit Playground Bluefruit
## Overview
Warning:
**Circuit Playground Bluefruit** is our third board in the Circuit Playground series, another step towards a perfect introduction to electronics and programming. We've taken the popular Circuit Playground Express and made it even better! Now the main chip is an nRF52840 microcontroller which is not only more powerful, but also comes with Bluetooth Low Energy support for wireless connectivity.
The board is round and has alligator-clip pads around it so you don't have to solder or sew to make it work. You can power it from USB, [a AAA battery pack](https://www.adafruit.com/products/727), or with a Lipoly battery (for advanced users). Circuit Playground Bluefruit has built-in USB support. Built in USB means you plug it in to program it and it just shows up, no special cable or adapter required. Just program your code into the board then take it on the go!
For folks who are comfortable with an early-release-version that does not support wireless capabilities, you can also try [MakeCode Maker](https://maker.makecode.com/)'s block-based GUI coding environment on this board.
Here's some of the great goodies baked in to each Circuit Playground Bluefruit:
- 1 x nRF52840 Cortex M4 processor with Bluetooth Low Energy support
- 10 x mini NeoPixels, each one can display any color
- 1 x Motion sensor (LIS3DH triple-axis accelerometer with tap detection, free-fall detection)
- 1 x Temperature sensor (thermistor)
- 1 x Light sensor (phototransistor). Can also act as a color sensor and pulse sensor.
- 1 x Sound sensor (MEMS microphone)
- 1 x Mini speaker with class D amplifier (7.5mm magnetic speaker/buzzer)
- 2 x Push buttons, labeled A and B
- 1 x Slide switch
- 8 x alligator-clip friendly input/output pins
- Includes I2C, UART, 6 pins that can do analog inputs, multiple PWM outputs
- Green "ON" LED so you know its powered
- Red "#13" LED for basic blinking
- Reset button
- 2 MB of SPI Flash storage, used primarily with CircuitPython to store code and libraries.
- MicroUSB port for programming and debugging
- USB port can act like serial port, keyboard, mouse, joystick or MIDI!
# Adafruit Circuit Playground Bluefruit
## Update Bootloader
Warning:
Older versions of Adafruit's nRF52840 boards were shipped with a bootloader that does not handle large UF2's, including CircuitPython 8.2.0 and later, and has other issues. To check whether you need to update the bootloader, double-click the reset button, and look in the `...BOOT` drive for **INFO\_UF2.TXT**.
Inside that file, check the version number of the bootloader. There are multiple version numbers. Look for the number just after "UF2 Bootloader" on the first line. See the picture below **It should be 0.6.1 or newer**.
The Adafruit nRF52 Bootloader can be upgraded/downgraded without any additional hardware. There are 3 different ways to update the bootloader, each has its pros and cons:
Warning: You **cannot** use the UF2 updater if your existing bootloader is version 0.3.x or earlier. You must use Arduino IDE or the Command Line.
- **Use UF2: ** This is the fastest and safest way to update bootloader. However, it requires your existing bootloader version is at least **0.4.0 ** and only work with nRF52840 (not nRF52832).
- **Use Arduino IDE** : work with all Adafruit nRF52 boards and bootloader version, typo free but may not be the latest bootloader version due to the BSP release cycle.
- **Use Command Line** : work with all boards and bootloader version (including 3rd party one). This command line uses the back-end of the Arduino IDE method above.
# Adafruit Circuit Playground Bluefruit
## Use UF2
This is the fastest and safest way to update bootloader. However, it requires your existing bootloader is at least **0.4.0 ** and only work with nRF52840 (not nRF52832) since UF2 make use of USB MSC interface.
Danger: You **cannot** use the UF2 updater if your existing bootloader is version 0.3.x or earlier. You must use Arduino IDE or the Command Line.
## Download update-bootloader UF2
You need a .`uf2` file containing the latest version of the bootloader. The most common updaters are linked below. For updaters for other boards, look for the [.uf2 files here](https://github.com/adafruit/Adafruit_nRF52_Bootloader/releases/latest) that begin with **update-...**
Info: Note if you click the link above, you must scroll down to the UF2 files that begin with the word update as the zip files do not include UF2s. Most users will click the appropriate green button below to select the file for their board.
[Feather nRF52840 Express bootloader updater UF2](https://github.com/adafruit/Adafruit_nRF52_Bootloader/releases/latest/update-feather_nrf52840_express_bootloader-*_nosd.uf2)
[Circuit Playground Bluefruit bootloader updater UF2](https://github.com/adafruit/Adafruit_nRF52_Bootloader/releases/latest/update-circuitplayground_nrf52840_bootloader-*_nosd.uf2)
[ItsyBitsy nRF52840 bootloader updater UF2](https://github.com/adafruit/Adafruit_nRF52_Bootloader/releases/latest/update-itsybitsy_nrf52840_express_bootloader-*_nosd.uf2)
[CLUE nRF52840 bootloader updater UF2](https://github.com/adafruit/Adafruit_nRF52_Bootloader/releases/latest/update-clue_nrf52840_bootloader-*_nosd.uf2)
[Feather Sense nRF52840 bootloader updater UF2](https://github.com/adafruit/Adafruit_nRF52_Bootloader/releases/latest/update-feather_nrf52840_sense_bootloader-*_nosd.uf2)
## Enter Bootloader Mode
Double-click the **Reset ** button on your board, and you will see the NeoPixel RGB LED turn green (identified by the arrow in the image). If it turns red, check the USB cable, try another USB port, etc.
**Note:** on **nRF52840 USB Key with TinyUF2 (PID 5199)** you need to hold its button while plugging into your PC.
## Drag & Drop UF2
You will see a new **BOOT** disk drive appear e.g **FTHR840BOOT**. Drag the downloaded **.** `uf2` file to **FTHR840BOOT. ** The LED will flash. Then, the **FTHR840BOOT** drive will disappear. That's it, you have successfully update your board to the latest version.
## Issues
If you download the wrong UF2 file for your board, dragging the file to the **...BOOT** drive will close the drive but will not update the firmware (as it is the firmware for the wrong board). You can check the **INFO\_UF2.TXT** on the board and see if the firmware was updated (likely with the wrong UF2 file it was not).
If you cannot find the correct UF2 check all the files in [https://github.com/adafruit/Adafruit\_nRF52\_Bootloader/releases](https://github.com/adafruit/Adafruit_nRF52_Bootloader/releases) for the correct UF2 (they all start with the word `update-boardname-bootloader-version.uf2` so scroll the list down to the files starting with u.
Non Adafruit board firmware updates can be found using this method also.
# Adafruit Circuit Playground Bluefruit
## Use Arduino IDE
Arduino IDE **Burn Bootloader** menu option will pick the correct bootloader binary for your selected board and prevent any command typos or other common errors.
Danger:
Info:
Pink: If you have previously installed CircuitPython on the board, double click the reset button prior to flashing the firmware to put it in bootloader mode.
If you have not already done so, set up Arduino IDE for nRF52, using the instructions in [Arduino Support Setup](https://learn.adafruit.com/adafruit-circuit-playground-bluefruit/arduino-support-setup).
Make sure no other program is attached to the serial port on the board, such as Mu, the Serial Monitor in Arduino, or a terminal program. Then, to start, select the correct board you are using under **Tools -\> Board**
Then select " **Bootloader DFU for Bluefruit nRF52**" for **Tools-\>Programmer**
**Double check all of the following: Board, Programmer...**
Then select **Tools-\>Burn Bootloader** to start the upgrade.
After receiving the new Bootloader over the serial connection, the old Bootloader will erase itself! The new bootloader will then be flashed. The process typically takes 30-60 seconds to complete. Make sure you see the " **Device programmed**" in the output log before launching Serial monitor or uploadinga new sketch.
```terminal
Upgrading target on /dev/ttyACM0 with DFU package /Adafruit_nRF52_Arduino/bootloader/feather_nrf52840_express/feather_nrf52840_express_bootloader-0.6.2_s140_6.1.1.zip. Flow control is disabled, Dual bank, Touch 1200
Touched serial port /dev/ttyACM0
Opened serial port /dev/ttyACM0
Starting DFU upgrade of type 3, SoftDevice size: 151016, bootloader size: 39000, application size: 0
Sending DFU start packet
Sending DFU init packet
Sending firmware file
########################################
########################################
########################################
########################################
########################################
########################################
########################################
########################################
########################################
############
Activating new firmware
DFU upgrade took 20.50154972076416s
Device programmed.
```
Drawbacks of this method are that you will need to install the Arduino IDE, and the bundled bootloader may not be the latest one. Check out the next page for a more advanced command line version.
# Adafruit Circuit Playground Bluefruit
## Use Command Line
Info:
## Download Bootloader Package
To update the bootloader you need a **.zip** file containing the latest version of the bootloader. The most common bootloader **.zip** files are linked below. For **.zip** files for other boards, look for the [.zip files here](https://github.com/adafruit/Adafruit_nRF52_Bootloader/releases/latest) that begin with the name of the board you want to update.
Info: Pick the download below for the board that you have. If you have a different board, look for the right .zip file for the board you have at the link just above.
[Bootloader .zip package for Adafruit Feather nRF52840 (latest version)](https://github.com/adafruit/Adafruit_nRF52_Bootloader/releases/latest/feather_nrf52840_express_bootloader-*.zip)
[Bootloader .zip package for Adafruit Feather nRF52840 Sense (latest version)](https://github.com/adafruit/Adafruit_nRF52_Bootloader/releases/latest/feather_nrf52840_sense_bootloader-*.zip)
[Bootloader .zip package for Adafruit CLUE (latest version)](https://github.com/adafruit/Adafruit_nRF52_Bootloader/releases/latest/clue_nrf52840_bootloader-*.zip)
[Bootloader .zip package for Circuit Playground Bluefruit (latest version)](https://github.com/adafruit/Adafruit_nRF52_Bootloader/releases/latest/circuitplayground_nrf52840_bootloader-*.zip)
[Bootloader .zip package for Adafruit ItsyBitsy nRF52840 (latest version)](https://github.com/adafruit/Adafruit_nRF52_Bootloader/releases/latest/itsybitsy_nrf52840_express_bootloader-*.zip)
Warning:
## Download **adafruit-nrfutil**
You will also need the utility program **adafruit-nrfutil,** which has slightly different names on different platforms.
### **adafruit-nrfutil** for Linux
On Linux, you can download and install **adafruit-nrfutil** by doing:
```terminal
pip3 install --user adafruit-nrfutil
```
### **adafruit-nrfutil** for macOS
On macOS, if you have **python3** and **pip3** installed, you can install via **pip3** , as above for Linux. Otherwise download the zip file **adafruit-nrfutil-macos...zip** from the link below, and then extract the file **adafruit-nrfutil** from the zip file.
[adafruit-nrfutil-macos for MacOS (in .zip file)](https://github.com/adafruit/Adafruit_nRF52_nrfutil/releases/latest/adafruit-nrfutil-*-macos.zip)
Then make **adafruit-nrfutil** executable by doing:
```terminal
chmod +x adafruit-nrfutil
```
### **adafruit-nrfutil** for Windows
Download the .zip file from this link, and extract the file **adafruit-nrfutil.exe**.
[adafruit-nrfutil.exe for Windows (in .zip file)](https://github.com/adafruit/Adafruit_nRF52_nrfutil/releases/latest/adafruit-nrfutil-*-win.zip)
## Update Bootloader
To update the bootloader, first connect the board, and then double-click the RESET button to get the ... **BOOT** drive to appear.
Info:
### Updating on Linux
Run a command similar to the one below in a shell window. **Substitute the name of the .zip file you downloaded above for the file given below**.
```terminal
adafruit-nrfutil --verbose dfu serial --package feather_nrf52840_express_bootloader-0.8.0_s140_6.1.1.zip -p /dev/ttyACM0 -b 115200 --singlebank --touch 1200
```
### Updating on macOS
Find out the device name for the connected board, by doing:
```terminal
ls /dev/cu.*
```
The device name will be something like `/dev/cu.usbmodem411`. Use this command, substituting the device name you've discovered. **Substitute the name of the .zip file you downloaded above for the file given below**. and the name of the .zip package you downloaded above. If you are running it other than where you downloaded **adafruit-nrfutil-macos** , change the path to the command accordingly. If you installed it via pip3, it's just called **adafruit-nrfutil** , and it should be in your `PATH`.
```terminal
./adafruit-nrfutil-macos --verbose dfu serial --package feather_nrf52840_express_bootloader-0.8.0_s140_6.1.1.zip -p /dev/cu.usbmodem411 -b 115200 --singlebank --touch 1200
```
### Updating on Windows
Use this command in the folder where you downloaded the other two files above. You'll need to specify the correct COM port, instead of `COMxx`. Look in **Device Manager-\>Ports** for the name of the COM port (it will be listed as a "USB Serial Device" on Windows 10) after you have double-clicked the RESET button. **Substitute the name of the .zip file you downloaded above for the file given below**.
```terminal
adafruit-nrfutil.exe --verbose dfu serial --package feather_nrf52840_express_bootloader-0.8.0_s140_6.1.1.zip --port COMxx -b 115200 --singlebank --touch 1200
```
### Output when Updating
When you run the **adafruit-nrfutil** program, you will see output similar to this (it will vary slightly depending on your OS).
```terminal
Upgrading target on COM29 with DFU package C:\Users\halbe\Desktop\update-feather-nrf52840-bootloader-0.8.0-windows\feather_nrf52840_express_bootloader-0.8.0_s140_6.1.1.zip. Flow control is disabled, Single bank, Touch 1200
Touched serial port COM29
Opened serial port COM29
Starting DFU upgrade of type 3, SoftDevice size: 151016, bootloader size: 39000, application size: 0
Sending DFU start packet
Sending DFU init packet
Sending firmware file
########################################
########################################
########################################
########################################
########################################
########################################
########################################
########################################
########################################
############
Activating new firmware
DFU upgrade took 21.119003295898438s
Device programmed.
```
Once done, click the RESET button again - the bootloader will be running!
# Adafruit Circuit Playground Bluefruit
## Guided Tour
Let us take you on a tour of your Circuit Playground Bluefruit, which we'll shorten to **CPB**.
# Power and Data
## Micro B USB connector
This is at the top of the board. We went with the tried and true micro-B USB connector for power and/or USB communication (bootloader, serial, HID, etc). Use with any computer with a standard data/sync cable.
## JST Battery Input
This is at the bottom of the board. You can take your CPB anywhere and power it from an external battery. This pin can take up 6V DC input, and has reverse-polarity, over-current and thermal protections. The circuitry inside will use either the battery input power or USB power, safely switching from one to the other. If both are connected, it will use whichever has the higher voltage. Works great with a Lithium Polymer battery or our 3xAAA battery packs with a JST connector on the end. There is no built in battery charging (so that you can use Alkaline _or_ Lithium batteries safely)
# Alligator/Croc Clip Pads
To make it super-easy to connect to the microcontroller, we have 14 connection pads. You can solder to them, use alligator/croc clips, sew with conductive thread, even use small metal screws!
Of the 14 pads, you get a wide range of power pins, I2C, UART, Analog In, Digital In/Out, PWM, and Analog Out.
Some of them can even sense the touch of your finger!
See the next pinouts page for more details!
# Microchips
The **brains** of the operation is the **nRF52840** Cortex M4 processor with Bluetooth Low Energy support. It sits at the top center and is what allows you to run CircuitPython or Arduino!
The **Bluetooth antenna** for the nRF52840 Bluetooth functionality is located in the center of the board. If you run into issues with Bluetooth range, make sure there's nothing near the antenna that might interfere, such as metallic surfaces!
We have added a storage chip, called SPI Flash. This is a very, very small disk drive, only 2 MB large. You can use this in Arduino or CircuitPython to store files. In CircuitPython this is where all your code lives, and what you see when you use the **CIRCUITPY** drive on your computer.
# LEDs
## Green ON LED
To the left of the USB connector. This LED lets you know that the CPB is powered on. If it's lit, power is good! If it's dim, flickering or off, there's a power problem and you will have problems. You can't disable this light, but you _can_ cover it with electrical tape if you want to make it black.
## Red #13 LED
To the right of the USB connector. This LED does double duty. Its connected with a series resistor to the digital #13 GPIO pin. It pulses nicely when the CPB is in bootloader mode, and its also handy for when you want an indicator LED. Many first projects blink this LED to prove that programming worked.
## 10 x Color NeoPixel LED
The ten LEDs surrounding the outer edge of the boards are all full color, RGB LEDs, each one can be set to any color in the rainbow. Great for beautiful lighting effects! The NeoPixels will also help you know when the bootloader is running (they will turn green) or if it failed to initialize USB when connected to a computer (they will turn red).
# Speaker
The CPB includes a speaker. It's not going to compete with your HiFi stereo, but it can play simple songs and tones.
The speaker is the squarish gray chunk on the bottom left of the board. There is a small class D amplifier connected to the speaker so it can get quite loud! Note: it won't sound good if too loud, so some experimentation may be necessary
The amplifier is connected to the PWM output **AUDIO** pin -- this pin is also available on one of the connection pads in the lower right.
If you do not want the internal speaker to make noise, you can turn it off using the shutdown control on pin **#11**
# Sensors
The Circuit Playground Bluefruit has a large number of sensor **inputs** that let you add all sorts of interactivity to your project.
## Light Sensor
There is an analog light sensor, [part number ALS-PT19](https://cdn-shop.adafruit.com/product-files/2748/2748%20datasheet.pdf), in the top left part of the board. This can be used to detect ambient light, with similar spectral response to the human eye.
This sensor is connect to analog pin **A8**. With Arduino, it will read between 0 and 1023 with higher values corresponding to higher light levels. A reading of about 300 is common for most indoor light levels. In CircuitPython, the returned range is scaled differently and is 0 to 65535.
With some clever code, you can use this as a color sensor or even a pulse sensor!
## Temperature Sensor
There is an NTC thermistor (Murata NCP15XH103F03RC) that we use for temperature sensing. While it isn't an all-in-one temperature sensor, with linear output, it's easy to calculate the temperature based on the analog voltage on analog pin **A9**. There's a 10K resistor connected to it as a pull down.
## Microphone Audio Sensor
A MEMS microphone can be used to detect audio levels and even perform basic FFT functions. Instead of an analog microphone, that requires an external op-amp and level management, we've decided to go with a PDM microphone. This is a digital mic, and is a lot smaller and less expensive! You will have to use the CircuitPython/Arduino support libraries to read the audio volume, you cannot read it like an analog voltage
## Motion Sensor
We can sense motion with an accelerometer. This sensor detects _acceleration_ which means it can be used to detect when its being moved around, as well as gravitational pull in order to detect orientation.
The LIS3DH 3-axis XYZ accelerometer can be used to detect tilt, gravity, motion, as well as 'tap' and 'double tap' strikes on the board. The LIS3DH is connected to an internal I2C pinset (not the same as the ones on the pads) and has an optional interrupt output on digital pin **D**** 24**.
## Capacitive Touch
The CPB has capacitive touch capabilities. This is a great way to sense human touch without additional components. Even animals will work if it's directly touching their skin!
On the Bluefruit you get **seven** capacitive touch pads: **A1 - A6 and TX**. Capacitive touch is supported in both CircuitPython and Arduino!
# Switches & Buttons
There are two large **A** and **B** buttons, connected to digital **D**** 4**(Left) and**D5**(Right) each. These are unconnected when not pressed, and connected to 3.3V when pressed, so they read HIGH. Set the pins**D4**(**BUTTON\_A**in CircuitPython) and**D5**(**BUTTON\_B** in CircuitPython) to use an internal pull-down resistor when reading these pins so they will read LOW when not pressed.
This small button in the center of the board is for **Resetting** the board. You can use this button to restart or reset the CPB.
If using Arduino or CircuitPython, press this button once to reset, double-click to enter the bootloader manually.
There is a single slide switch near the center bottom of the Circuit Playground Bluefruit. It is connected to digital **D7**. The switch is unconnected when slid to the left and connected to ground when slid to the right. We set pin D7 to use an internal pull-up resistor so that the switch will read HIGH when slid to the left and LOW when slid to the right.
This is not an on-off switch, but you can use code to have this switch control how you want your project to behave
Note that you need to use an internal _pull-up_ for the slide switch, but an internal _pull-down_ for the push-buttons.
# Adafruit Circuit Playground Bluefruit
## Pinouts
Despite having only 14 pads with 8 general purpose I/O pins available, there are a _lot_ of possibilities with Circuit Playground Bluefruit. We went over all the internals in the last page. On this page we'll go through each pin/pad to explain what you can do with it.
**Other than the Audio pad, no external I/O pads are shared with internal sensors/devices, so you do not need to worry about 'conflicting' pins or interactions!**
[Click here to view a PDF version of the pinout diagram](https://github.com/adafruit/Adafruit-Circuit-Playground-Bluefruit-PCB/blob/master/Adafruit%20Circuit%20Playground%20Bluefruit%20pinout.pdf)
# Power Pads
There are 6 power pads available, equally spaced around the perimeter.
- **GND** - there are 3 x **Ground** pads. They are all connected together, and are all the signal/power ground connections
- **3.3V** - there are two **3.3 Volt output** pads. They are connected to the output of the onboard regulator. The regulator can provide about 500mA max, but that includes all the built in parts too! So you should roughly budget about 300mA available for your usage (450mA if you are not using the onboard NeoPixels)
- **Vout** - there is one **Voltage Output** pad. This is a special power pad, it will be connected to _either_ the USB power or the battery input, whichever has the higher voltage. This output does not connect to the regulator so **you can draw as much current as your USB port / Battery can provide**. There is a resettable fuse on this pin, so you can draw about 500mA continuous, and 1 Amp peak before it will trip. If the fuse trips, just wait a minute and it will automatically reset
If you want to connect chips, sensors, and low power electronics that requires 3.3V clean power, use the **3.3V** pads.
If you want to connect servos, NeoPixels, DotStars or other high power electronics that are OK up to 5V, use the **Vout** pad.
# Input/Output Pads
Next we will cover the 8 GPIO (General Purpose Input Ouput) pins! For reference you may want to also check out the datasheet-reference in the downloads section for the core nRF52840. We picked pins that have _a lot_ of capabilities.
## Common to all pads
**All the GPIO pads can be used as digital inputs, digital outputs, for LEDs, buttons and switches.** In addition, A1-A6 can be used as analog inputs (12-bit ADC) ( **TX** and **Audio** can not!). All but **Audio** can be used for capacitive touch. All pads can also be used as hardware interrupt inputs.
Each pad can provide up to ~20mA of current. Don't connect a motor or other high-power component directly to the pins! [Instead, use a transistor to power the DC motor on/off](http://learn.adafruit.com/adafruit-arduino-lesson-13-dc-motors "Link: http://learn.adafruit.com/adafruit-arduino-lesson-13-dc-motors")
All of the GPIO pads are 3.3V output level, and should not be used with 5V inputs. In general, most 5V devices are OK with 3.3V output though.
Other than **Audio** , which is shared with the speaker, all of the pads are completely 'free' pins, they are not used by the USB connection, LEDs, sensors, etc so you never have to worry about interfering with them when programming.
# Each Pin!
Let's start with **Audio** which is in the bottom right corner, and work our way counter-clockwise. Because the nRF52840 is flexible with PWM pins, you can make any of the pins PWM outputs
- **Audio** (a.k.a **D12** ) - This is a designated pin that is OK with high speed PWM signal, so it's great for playing basic audio clips - it's also connected to the little speaker on board. In can be digital I/O, but if you do that it will interfere with the built-in speaker. This is the one pin that cannot be used for capacitive touch.
- **A1** **/ D6** - This pin can be digital I/O, or analog input and can be capacitive touch sensor
- **A2** **/ D9** - This pin can be digital I/O, or analog input and can be capacitive touch sensor
- **A3** **/ D10** - This pin can be digital I/O, or analog input and can be capacitive touch sensor
- **A4** **/ SCL / D3** - This pin can be digital I/O, or analog input. This pin is also the designated **I2C SCL** pin, and can be capacitive touch sensor
- **A5** **/ SDA / D2** - This pin can be digital I/O, or analog input. This pin is also the designated **I2C SDA** pin, and can be capacitive touch sensor
- **A6** **/ RX / D0** - This pin can be digital I/O, or analog Input. This pin has PWM output, **Serial Receive,** and can be capacitive touch sensor
- **TX** **/ D1** - This pin can be digital I/O. This pin has PWM output, **Serial Transmit,** and can be capacitive touch sensor
# Internally Used Pins!
These are the names of the pins that are used for built in sensors and such! CircuitPython has more user friendly names available as well for some pins with things like buttons and LEDs on them - these are included in parentheses where applicable. Both names will work in CircuitPython!
- **D4 (BUTTON\_A)** - Left Button A
- **D5 (BUTTON\_B)** - Right Button B
- **D7 (SLIDE\_SWITCH)**- Slide Switch
- **D8 (NEOPIXEL)** - Built-in 10 NeoPixels
- **D11 (SPEAKER\_SHUTDOWN**; in CircuitPython, use `board.SPEAKER_ENABLE`**)** - Power control to the speaker amp, pulled up by default. Set to output and LOW to turn off the speaker and save power.
- **D12 / AUDIO (****SPEAKER)** - Speaker analog output
- **D13** - Red LED
- **A8 (LIGHT)** - Light Sensor
- **A9 (TEMPERATURE)** - Temperature Sensor
- **D24** - PDM mic data
- **D25** - PDM mic clock
- **D26** - Internal I2C SCL for accelerometer
- **D27** - Accelerometer interrupt
- **D28** - Internal I2C SDA for accelerometer
- **D29 ~ D34** - QSPI FLASH chip pins
- **D35** - Sensor + NeoPixel power pin, default is pulled LOW (to enable power to sensors and NeoPixel). Set to output and HIGH to turn off power to NeoPixels and light/thermistor/microphone. Accelerometer does not get turned off (so you can do shake-to-wake). Speaker shutdown pin is different as well
# Debug Interface
There are three **debug pads** on the back of the Circuit Playground Bluefruit below the "GROUND" in the PLAYGROUND label.
Left to right they are:
- **SWCLK**
- **SWDIO**
- **RESET**
# Adafruit Circuit Playground Bluefruit
## What is CircuitPython?
CircuitPython is a programming language designed to simplify experimenting and learning to program on low-cost microcontroller boards. It makes getting started easier than ever with no upfront desktop downloads needed. Once you get your board set up, open any text editor, and get started editing code. It's that simple.
# CircuitPython is based on Python
Python is the fastest growing programming language. It's taught in schools and universities. It's a high-level programming language which means it's designed to be easier to read, write and maintain. It supports modules and packages which means it's easy to reuse your code for other projects. It has a built in interpreter which means there are no extra steps, like _compiling_, to get your code to work. And of course, Python is Open Source Software which means it's free for anyone to use, modify or improve upon.
CircuitPython adds hardware support to all of these amazing features. If you already have Python knowledge, you can easily apply that to using CircuitPython. If you have no previous experience, it's really simple to get started!
## Why would I use CircuitPython?
CircuitPython is designed to run on microcontroller boards. A microcontroller board is a board with a microcontroller chip that's essentially an itty-bitty all-in-one computer. The board you're holding is a microcontroller board! CircuitPython is easy to use because all you need is that little board, a USB cable, and a computer with a USB connection. But that's only the beginning.
Other reasons to use CircuitPython include:
- **You want to get up and running quickly.** Create a file, edit your code, save the file, and it runs immediately. There is no compiling, no downloading and no uploading needed.
- **You're new to programming.** CircuitPython is designed with education in mind. It's easy to start learning how to program and you get immediate feedback from the board.
- **Easily update your code.** Since your code lives on the disk drive, you can edit it whenever you like, you can also keep multiple files around for easy experimentation.
- **The serial console and REPL.** These allow for live feedback from your code and interactive programming.
- **File storage.** The internal storage for CircuitPython makes it great for data-logging, playing audio clips, and otherwise interacting with files.
- **Strong hardware support.** CircuitPython has builtin support for microcontroller hardware features like digital I/O pins, hardware buses (UART, I2C, SPI), audio I/O, and other capabilities. There are also many libraries and drivers for sensors, breakout boards and other external components.
- **It's Python!** Python is the fastest-growing programming language. It's taught in schools and universities. CircuitPython is almost-completely compatible with Python. It simply adds hardware support.
This is just the beginning. CircuitPython continues to evolve, and is constantly being updated. Adafruit welcomes and encourages feedback from the community, and incorporate it into the development of CircuitPython. That's the core of the open source concept. This makes CircuitPython better for you and everyone who uses it!
# Adafruit Circuit Playground Bluefruit
## CircuitPython on Circuit Playground Bluefruit
# Install or Update CircuitPython
Follow this quick step-by-step to install or update CircuitPython on your Circuit Playground Bluefruit.
[Download the latest version of CircuitPython for this board via circuitpython.org](https://circuitpython.org/board/circuitplayground_bluefruit/)
**Click the link above and download the latest UF2 file**
Download and save it to your Desktop (or wherever is handy)
Plug your Circuit Playground Bluefruit into your computer using a known-good data-capable USB cable.
**A lot of people end up using charge-only USB cables and it is very frustrating! So make sure you have a USB cable you know is good for data sync.**
Double-click the small **Reset** button in the middle of the CPB (indicated by the red arrow in the image). The ten NeoPixel LEDs will all turn red, and then will all turn green. If they turn all red and stay red, check the USB cable, try another USB port, etc. The little red LED next to the USB connector will pulse red - this is ok!
If double-clicking doesn't work the first time, try again. Sometimes it can take a few tries to get the rhythm right!
(If double-clicking doesn't do it, try a single-click!)
You will see a new disk drive appear called **CPLAYBTBOOT**.
Drag the **adafruit\_circuitpython\_etc.uf2** file to **CPLAYBTBOOT.**
The LEDs will turn red. Then, the **CPLAYBTBOOT** drive will disappear and a new disk drive called **CIRCUITPY** will appear.
That's it, you're done! :)
# Adafruit Circuit Playground Bluefruit
## Circuit Playground Bluefruit CircuitPython Libraries
The Circuit Playground Bluefruit is packed full of features like Bluetooth and NeoPixel LEDs. Now that you have CircuitPython installed on your Circuit Playground Bluefruit, you'll need to install a base set of CircuitPython libraries to use the features of the board with CircuitPython.
Follow these steps to get the necessary libraries installed.
# Installing CircuitPython Libraries on Circuit Playground Bluefruit
If you do not already have a **lib** folder on your **CIRCUITPY** drive, create one now.
Then, download the CircuitPython library bundle that matches your version of CircuitPython from CircuitPython.org.
[Download the latest library bundle from circuitpython.org](https://circuitpython.org/libraries)
The bundle download as a .zip file. Extract the file. Open the resulting folder.
Open the **lib** folder found within.
Once inside, you'll find a lengthy list of folders and .mpy files. To install a CircuitPython library, you drag the file or folder from the **bundle lib folder** to **the lib folder on your CIRCUITPY drive**.
Copy the following folders and files **from the bundle lib folder** to **the** **lib folder on your CIRCUITPY drive** :
- **adafruit\_ble**
- **adafruit\_bluefruit\_connect**
- **adafruit\_bus\_device**
- **adafruit\_circuitplayground**
- **adafruit\_gizmo**
- **adafruit\_hid**
- **adafruit\_lis3dh.mpy**
- **adafruit\_thermistor.mpy**
- **neopixel.mpy**
Your lib folder should look like the image on the left.
Now you're all set to use CircuitPython with the features of the Circuit Playground Bluefruit!
# Adafruit Circuit Playground Bluefruit
## Getting Started with BLE and CircuitPython
# Guides
- [Getting Started with CircuitPython and Bluetooth Low Energy](https://learn.adafruit.com/circuitpython-nrf52840) - Get started with CircuitPython, the Adafruit nRF52840 and the Bluefruit LE Connect app.
- [BLE Light Switch with Feather nRF52840 and Crickit](https://learn.adafruit.com/bluetooth-light-switch-with-crickit-and-nrf52840) - Control a robot finger from across the room to flip on and off the lights!
- [Color Remote with Circuit Playground Bluefruit](https://learn.adafruit.com/color-remote-with-circuit-playground-bluefruit) - Mix NeoPixels wirelessly with a Bluetooth LE remote control!
- [MagicLight Bulb Color Mixer with Circuit Playground Bluefruit](https://learn.adafruit.com/magiclight-bulb-mixer) - Mix colors on a MagicLight Bulb wirelessly with a Bluetooth LE remote control.
- [Bluetooth Turtle Bot with CircuitPython and Crickit](https://learn.adafruit.com/bluetooth-turtle-bot-with-circuitpython-and-crickit) - Build your own Bluetooth controlled turtle rover!
- [Wooden NeoPixel Xmas Tree](https://learn.adafruit.com/wooden-neopixel-xmas-tree) - Cut a Christmas tree of wood and mount some NeoPixels in the tree to create a festive yuletide light display.
- [Bluefruit TFT Gizmo ANCS Notifier for iOS](https://learn.adafruit.com/ancs-gizmo) - Circuit Playground Bluefruit displays your iOS notification icons so you know when there's fresh activity!
- [Bluefruit Playground Hide and Seek](https://learn.adafruit.com/hide-n-seek-bluefruit-ornament) - Use Circuit Playground Bluefruit devices to create a colorful signal strength-based proximity detector!
- [Snow Globe with Circuit Playground Bluefruit](https://learn.adafruit.com/snow-globe-bluefruit-cpb) - Make your own festive (or creatively odd!) snow globe with custom lighting effects and Bluetooth control.
- [Bluetooth Controlled NeoPixel Lightbox](https://learn.adafruit.com/bluetooth-neopixel-lightbox) - Great for tracing and writing, this lightbox lets you adjust color and brightness with your phone.
- [Circuit Playground Bluefruit NeoPixel Animation and Color Remote Control](https://learn.adafruit.com/circuit-playground-bluefruit-neopixel-animation-and-color-remote-control) - Control NeoPixel colors and animation remotely over Bluetooth with the Circuit Playground Bluefruit!
- [Circuit Playground Bluetooth Cauldron](https://learn.adafruit.com/cpx-cauldron) - Build a Bluetooth Controlled Light Up Cauldron.
- [NeoPixel Badge Lanyard with Bluetooth LE](https://learn.adafruit.com/bluetooth-neopixel-badge-lanyard) - Light up your convention badge and control colors with your phone!
- [CircuitPython BLE Controlled NeoPixel Hat](https://learn.adafruit.com/circuitpython-feather-ble-neopixel-hat) - Wireless control NeoPixels on your wearables!
- [Bluefruit nRF52 Feather Learning Guide](https://learn.adafruit.com/bluefruit-nrf52-feather-learning-guide) - Get started now with our most powerful Bluefruit board yet!
- [CircusPython: Jump through Hoops with CircuitPython Bluetooth LE](https://learn.adafruit.com/circuspython-jump-through-hoops-with-bluetooth-le) - Blinka jumps through a ring of fire, controlled via Bluetooth LE and the Bluefruit LE Connect app!
- [A CircuitPython BLE Remote Control On/Off Switch](https://learn.adafruit.com/circuitpython-ble-remote-control-on-off) - Make a remote control on/off switch for a computer with CircuitPython and BLE.
- [NeoPixel Infinity Cube](https://learn.adafruit.com/neopixel-infinity-cube) - Build a 3D printed, Bluetooth controlled Mirrored Acrylic and NeoPixel Infinity cube.
- [CircuitPython BLE Crickit Rover](https://learn.adafruit.com/circuitpython-ble-crickit-rover) - Purple Robot with Feather nRF52840 and Crickit plus NeoPixel underlighting!
- [Circuit Playground Bluefruit Pumpkin with Lights and Sounds](https://learn.adafruit.com/pumpkin-with-circuit-playground-bluefruit) - Add the Circuit Playground Bluefruit and STEMMA speaker to an inexpensive plastic pumpkin.
- [No-Solder LED Disco Tie with Bluetooth](https://learn.adafruit.com/no-solder-circuit-playground-bluetooth-disco-tie) - Build an LED tie controlled by Bluetooth LE.
- [Bluetooth Remote Control for the Lego Droid Developer Kit](https://learn.adafruit.com/bluetooth-remote-for-lego-droid) - Reinvigorating the Lego Star Wars Droid Developer Kit with an Adafruit powered remote control using Bluetooth LE.
# Adafruit Circuit Playground Bluefruit
## Installing the Mu Editor
Mu is a simple code editor that works with the Adafruit CircuitPython boards. It's written in Python and works on Windows, MacOS, Linux and Raspberry Pi. The serial console is built right in so you get immediate feedback from your board's serial output!
Info: Mu is our recommended editor - please use it (unless you are an experienced coder with a favorite editor already!). While it has been announced end of life in 2026, it still works fine.
You are free to use whatever text editor you wish along with a terminal program to connect to the CircuitPython REPL. Thonny is one such editor.
## Download and Install Mu
Download Mu from [https://codewith.mu](https://codewith.mu/).
Click the **Download** link for downloads and installation instructions.
Click **Start Here ** to find a wealth of other information, including extensive tutorials and and how-to's.
Warning:
## Starting Up Mu
The first time you start Mu, you will be prompted to select your 'mode' - you can always change your mind later. For now please select **CircuitPython**!
The current mode is displayed in the lower right corner of the window, next to the "gear" icon. If the mode says "Microbit" or something else, click the **Mode** button in the upper left, and then choose "CircuitPython" in the dialog box that appears.
Mu attempts to auto-detect your board on startup, so if you do not have a CircuitPython board plugged in with a **CIRCUITPY** drive available, Mu will inform you where it will store any code you save until you plug in a board.
To avoid this warning, plug in a board and ensure that the **CIRCUITPY** drive is mounted before starting Mu.
## Using Mu
You can now explore Mu! The three main sections of the window are labeled below; the button bar, the text editor, and the serial console / REPL.
Now you're ready to code! Let's keep going...
# Adafruit Circuit Playground Bluefruit
## Creating and Editing Code
One of the best things about CircuitPython is how simple it is to get code up and running. This section covers how to create and edit your first CircuitPython program.
To create and edit code, all you'll need is an editor. There are many options. **Adafruit strongly recommends using Mu! It's designed for CircuitPython, and it's really simple and easy to use, with a built in serial console!**
If you don't or can't use Mu, there are a number of other editors that work quite well. The [Recommended Editors page](https://learn.adafruit.com/welcome-to-circuitpython/recommended-editors) has more details. Otherwise, make sure you do "Eject" or "Safe Remove" on Windows or "sync" on Linux after writing a file if you aren't using Mu. (This was formerly not a problem on macOS, but see the warning below.)
Warning: macOS Sonoma 14.1 introduced a bug that delays writes to small drives such as CIRCUITPY drives. This caused errors when saving files to CIRCUITPY. There is a [workaround](https://learn.adafruit.com/welcome-to-circuitpython/troubleshooting#macos-sonoma-14-dot-x-disk-errors-writing-to-circuitpy-3160304). The bug was fixed in Sonoma 14.4, but at the cost of greatly slowed writes to drives 1GB or smaller.
## Creating Code
Installing CircuitPython generates a **code.py** file on your **CIRCUITPY** drive. To begin your own program, open your editor, and load the **code.py** file from the **CIRCUITPY** drive.
If you are using Mu, click the **Load** button in the button bar, navigate to the **CIRCUITPY** drive, and choose **code.py**.
Copy and paste the following code into your editor:
```python
import board
import digitalio
import time
led = digitalio.DigitalInOut(board.LED)
led.direction = digitalio.Direction.OUTPUT
while True:
led.value = True
time.sleep(0.5)
led.value = False
time.sleep(0.5)
```
Danger: The KB2040, QT Py , Qualia, and the Trinkeys do not have a built-in little red LED! There is an addressable RGB NeoPixel LED. The above example will NOT work on the KB2040, QT Py, Qualia, or the Trinkeys!
If you're using a KB2040, QT Py, Quaila, or a Trinkey, or any other board without a single-color LED that can blink, please download the [NeoPixel blink example](https://github.com/adafruit/Adafruit_Learning_System_Guides/blob/master/Welcome_to_CircuitPython/code.py).
Info:
It will look like this. Note that under the `while True:` line, the next four lines begin with four spaces to indent them, and they're indented exactly the same amount. All the lines before that have no spaces before the text.
Save the **code.py** file on your **CIRCUITPY** drive.
The little LED should now be blinking. Once per half-second.
Congratulations, you've just run your first CircuitPython program!
Info: On most boards you'll find a tiny red LED. On the ItsyBitsy nRF52840, you'll find a tiny blue LED. On QT Py M0, QT Py RP2040, Qualia, and the Trinkey series, you will find only an RGB NeoPixel LED.
## Editing Code
To edit code, open the **code.py** file on your **CIRCUITPY** drive into your editor.
Make the desired changes to your code. Save the file. That's it!
### Your code changes are run as soon as the file is done saving.
There's one warning before you continue...
Danger:
The CircuitPython code on your board detects when the files are changed or written and will automatically re-start your code. This makes coding very fast because you save, and it re-runs. If you unplug or reset the board before your computer finishes writing the file to your board, you can corrupt the drive. If this happens, you may lose the code you've written, so it's important to backup your code to your computer regularly.
There are a couple of ways to avoid filesystem corruption.
### **1. Use an editor that writes out the file completely when you save it.**
Check out the [Recommended Editors page](https://learn.adafruit.com/welcome-to-circuitpython/recommended-editors) for details on different editing options.
Info:
### **2. Eject or Sync the Drive After Writing**
If you are using one of our not-recommended-editors, not all is lost! You can still make it work.
On Windows, you can Eject or Safe Remove the **CIRCUITPY** drive. It won't actually eject, but it will force the operating system to save your file to disk. On Linux, use the **sync** command in a terminal to force the write to disk.
You also need to do this if you use Windows Explorer or a Linux graphical file manager to drag a file onto **CIRCUITPY**.
###
Don't worry! Corrupting the drive isn't the end of the world (or your board!). If this happens, follow the steps found on the [Troubleshooting](https://learn.adafruit.com/welcome-to-circuitpython/troubleshooting) page of every board guide to get your board up and running again.
Info: If you are having trouble saving code on Windows 10, try including this code snippet at the top of code.py:
```python
import supervisor
supervisor.runtime.autoreload = False
```
## Back to Editing Code...
Now! Let's try editing the program you added to your board. Open your **code.py** file into your editor. You'll make a simple change. Change the first `0.5` to `0.1`. The code should look like this:
```python
import board
import digitalio
import time
led = digitalio.DigitalInOut(board.LED)
led.direction = digitalio.Direction.OUTPUT
while True:
led.value = True
time.sleep(0.1)
led.value = False
time.sleep(0.5)
```
Leave the rest of the code as-is. Save your file. See what happens to the LED on your board? Something changed! Do you know why?
You don't have to stop there! Let's keep going. Change the second `0.5` to `0.1` so it looks like this:
```
while True:
led.value = True
time.sleep(0.1)
led.value = False
time.sleep(0.1)
```
Now it blinks really fast! You decreased the both time that the code leaves the LED on and off!
Now try increasing both of the `0.1` to `1`. Your LED will blink much more slowly because you've increased the amount of time that the LED is turned on and off.
Well done! You're doing great! You're ready to start into new examples and edit them to see what happens! These were simple changes, but major changes are done using the same process. Make your desired change, save it, and get the results. That's really all there is to it!
# Naming Your Program File
CircuitPython looks for a code file on the board to run. There are four options: **code.txt** , **code.py** , **main.txt** and **main.py**. CircuitPython looks for those files, in that order, and then runs the first one it finds. While **code.py** is the recommended name for your code file, it is important to know that the other options exist. If your program doesn't seem to be updating as you work, make sure you haven't created another code file that's being read instead of the one you're working on.
# Adafruit Circuit Playground Bluefruit
## Connecting to the Serial Console
One of the staples of CircuitPython (and programming in general!) is something called a "print statement". This is a line you include in your code that causes your code to output text. A print statement in CircuitPython (and Python) looks like this:
`print("Hello, world!")`
This line in your code.py would result in:
`Hello, world!`
However, these print statements need somewhere to display. That's where the serial console comes in!
The serial console receives output from your CircuitPython board sent over USB and displays it so you can see it. This is necessary when you've included a print statement in your code and you'd like to see what you printed. It is also helpful for troubleshooting errors, because your board will send errors and the serial console will display those too.
The serial console requires an editor that has a built in terminal, or a separate terminal program. A terminal is a program that gives you a text-based interface to perform various tasks.
# Are you using Mu?
If so, good news! The serial console **is built into Mu** and will **autodetect your board** making using the serial console _really really easy_.
First, make sure your CircuitPython board is plugged in.
If you open Mu without a board plugged in, you may encounter the error seen here, letting you know no CircuitPython board was found and indicating where your code will be stored until you plug in a board.
[If you are using Windows 7, make sure you installed the drivers](https://learn.adafruit.com/welcome-to-circuitpython/windows-7-and-8-1-drivers).
Once you've opened Mu with your board plugged in, look for the **Serial** button in the button bar and click it.
The Mu window will split in two, horizontally, and display the serial console at the bottom.
Info:
## Serial Console Issues or Delays on Linux
If you're on Linux, and are seeing multi-second delays connecting to the serial console, or are seeing "AT" and other gibberish when you connect, then the `modemmanager` service might be interfering. Just remove it; it doesn't have much use unless you're still using dial-up modems.
To remove `modemmanager`, type the following command at a shell:
```terminal
sudo apt purge modemmanager
```
## Setting Permissions on Linux
On Linux, if you see an error box something like the one below when you press the **Serial** button, you need to add yourself to a user group to have permission to connect to the serial console.
On Ubuntu and Debian, add yourself to the **dialout** group by doing:
```terminal
sudo adduser $USER dialout
```
After running the command above, reboot your machine to gain access to the group. On other Linux distributions, the group you need may be different. See the [Advanced Serial Console on Linux](https://learn.adafruit.com/welcome-to-circuitpython/advanced-serial-console-on-linux) for details on how to add yourself to the right group.
# Using Something Else?
If you're not using Mu to edit, or if for some reason you are not a fan of its built in serial console, you can run the serial console from a separate program.
Windows requires you to download a terminal program. [Check out the Advanced Serial Console on Windows page for more details.](../../../../welcome-to-circuitpython/advanced-serial-console-on-windows)
MacOS has serial connection programs you can run in Terminal. [Check the Advanced Serial Console on Mac page for more details.](../../../../welcome-to-circuitpython/advanced-serial-console-on-mac-and-linux)
Linux has multiple terminal programs included options are available for download. [Check the Advanced Serial Console on Linux page for more details.](https://learn.adafruit.com/welcome-to-circuitpython/advanced-serial-console-on-linux)
Once connected, you'll see something like the following.
# Adafruit Circuit Playground Bluefruit
## Interacting with the Serial Console
Once you've successfully connected to the serial console, it's time to start using it.
The code you wrote earlier has no output to the serial console. So, you're going to edit it to create some output.
Open your code.py file into your editor, and include a `print` statement. You can print anything you like! Just include your phrase between the quotation marks inside the parentheses. For example:
```python
import board
import digitalio
import time
led = digitalio.DigitalInOut(board.LED)
led.direction = digitalio.Direction.OUTPUT
while True:
print("Hello, CircuitPython!")
led.value = True
time.sleep(1)
led.value = False
time.sleep(1)
```
Save your file.
Now, let's go take a look at the window with our connection to the serial console.
Excellent! Our print statement is showing up in our console! Try changing the printed text to something else.
```python
import board
import digitalio
import time
led = digitalio.DigitalInOut(board.LED)
led.direction = digitalio.Direction.OUTPUT
while True:
print("Hello back to you!")
led.value = True
time.sleep(1)
led.value = False
time.sleep(1)
```
Keep your serial console window where you can see it. Save your file. You'll see what the serial console displays when the board reboots. Then you'll see your new change!
The `Traceback (most recent call last):` is telling you the last thing your board was doing before you saved your file. This is normal behavior and will happen every time the board resets. This is really handy for troubleshooting. Let's introduce an error so you can see how it is used.
Delete the `e` at the end of `True` from the line `led.value = True` so that it says `led.value = Tru`
```python
import board
import digitalio
import time
led = digitalio.DigitalInOut(board.LED)
led.direction = digitalio.Direction.OUTPUT
while True:
print("Hello back to you!")
led.value = Tru
time.sleep(1)
led.value = False
time.sleep(1)
```
Save your file. You will notice that your red LED will stop blinking, and you may have a colored status LED blinking at you. This is because the code is no longer correct and can no longer run properly. You need to fix it!
Usually when you run into errors, it's not because you introduced them on purpose. You may have 200 lines of code, and have no idea where your error could be hiding. This is where the serial console can help. Let's take a look!
The `Traceback (most recent call last):` is telling you that the last thing it was able to run was `line 10` in your code. The next line is your error: `NameError: name 'Tru' is not defined`. This error might not mean a lot to you, but combined with knowing the issue is on line 10, it gives you a great place to start!
Go back to your code, and take a look at line 10. Obviously, you know what the problem is already. But if you didn't, you'd want to look at line 10 and see if you could figure it out. If you're still unsure, try googling the error to get some help. In this case, you know what to look for. You spelled True wrong. Fix the typo and save your file.
Nice job fixing the error! Your serial console is streaming and your red LED Is blinking again.
The serial console will display any output generated by your code. Some sensors, such as a humidity sensor or a thermistor, receive data and you can use print statements to display that information. You can also use print statements for troubleshooting, which is called "print debugging". Essentially, if your code isn't working, and you want to know where it's failing, you can put print statements in various places to see where it stops printing.
The serial console has many uses, and is an amazing tool overall for learning and programming!
# Adafruit Circuit Playground Bluefruit
## The REPL
The other feature of the serial connection is the **R** ead- **E** valuate **-**** P **rint-** L**oop, or REPL. The REPL allows you to enter individual lines of code and have them run immediately. It's really handy if you're running into trouble with a particular program and can't figure out why. It's interactive so it's great for testing new ideas.
## Entering the REPL
To use the REPL, you first need to be connected to the serial console. Once that connection has been established, you'll want to press **CTRL+C**.
If there is code running, in this case code measuring distance, it will stop and you'll see `Press any key to enter the REPL. Use CTRL-D to reload.` Follow those instructions, and press any key on your keyboard.
The `Traceback (most recent call last):` is telling you the last thing your board was doing before you pressed Ctrl + C and interrupted it. The `KeyboardInterrupt` is you pressing CTRL+C. This information can be handy when troubleshooting, but for now, don't worry about it. Just note that it is expected behavior.
If your **code.py** file is empty or does not contain a loop, it will show an empty output and `Code done running.`. There is no information about what your board was doing before you interrupted it because there is no code running.
If you have no **code.py** on your **CIRCUITPY** drive, you will enter the REPL immediately after pressing CTRL+C. Again, there is no information about what your board was doing before you interrupted it because there is no code running.
Regardless, once you press a key you'll see a `>>>` prompt welcoming you to the REPL!
If you have trouble getting to the `>>>` prompt, try pressing Ctrl + C a few more times.
The first thing you get from the REPL is information about your board.
This line tells you the version of CircuitPython you're using and when it was released. Next, it gives you the type of board you're using and the type of microcontroller the board uses. Each part of this may be different for your board depending on the versions you're working with.
This is followed by the CircuitPython prompt.
## Interacting with the REPL
From this prompt you can run all sorts of commands and code. The first thing you'll do is run `help()`. This will tell you where to start exploring the REPL. To run code in the REPL, type it in next to the REPL prompt.
Type `help()` next to the prompt in the REPL.
Then press enter. You should then see a message.
First part of the message is another reference to the version of CircuitPython you're using. Second, a URL for the CircuitPython related project guides. Then... wait. What's this? To list built-in modules type `help("modules").` Remember the modules you learned about while going through creating code? That's exactly what this is talking about! This is a perfect place to start. Let's take a look!
Type `help("modules")` into the REPL next to the prompt, and press enter.
This is a list of all the core modules built into CircuitPython, including `board`. Remember, `board` contains all of the pins on the board that you can use in your code. From the REPL, you are able to see that list!
Type `import board` into the REPL and press enter. It'll go to a new prompt. It might look like nothing happened, but that's not the case! If you recall, the `import` statement simply tells the code to expect to do something with that module. In this case, it's telling the REPL that you plan to do something with that module.
Next, type `dir(board)` into the REPL and press enter.
This is a list of all of the pins on your board that are available for you to use in your code. Each board's list will differ slightly depending on the number of pins available. Do you see `LED`? That's the pin you used to blink the red LED!
The REPL can also be used to run code. Be aware that **any code you enter into the REPL isn't saved** anywhere. If you're testing something new that you'd like to keep, make sure you have it saved somewhere on your computer as well!
Every programmer in every programming language starts with a piece of code that says, "Hello, World." You're going to say hello to something else. Type into the REPL:
`print("Hello, CircuitPython!")`
Then press enter.
That's all there is to running code in the REPL! Nice job!
You can write single lines of code that run stand-alone. You can also write entire programs into the REPL to test them. Remember that nothing typed into the REPL is saved.
There's a lot the REPL can do for you. It's great for testing new ideas if you want to see if a few new lines of code will work. It's fantastic for troubleshooting code by entering it one line at a time and finding out where it fails. It lets you see what modules are available and explore those modules.
Try typing more into the REPL to see what happens!
Warning:
# Returning to the Serial Console
When you're ready to leave the REPL and return to the serial console, simply press **CTRL+D**. This will reload your board and reenter the serial console. You will restart the program you had running before entering the REPL. In the console window, you'll see any output from the program you had running. And if your program was affecting anything visual on the board, you'll see that start up again as well.
You can return to the REPL at any time!
# Adafruit Circuit Playground Bluefruit
## CircuitPython Libraries
Danger:
Each CircuitPython program you run needs to have a lot of information to work. The reason CircuitPython is so simple to use is that most of that information is stored in other files and works in the background. These files are called _libraries_. Some of them are built into CircuitPython. Others are stored on your **CIRCUITPY** drive in a folder called **lib**. Part of what makes CircuitPython so great is its ability to store code separately from the firmware itself. Storing code separately from the firmware makes it easier to update both the code you write and the libraries you depend.
Your board may ship with a **lib** folder already, it's in the base directory of the drive. If not, simply create the folder yourself. When you first install CircuitPython, an empty **lib** directory will be created for you.
CircuitPython libraries work in the same way as regular Python modules so the [Python docs](https://docs.python.org/3/tutorial/modules.html) are an excellent reference for how it all should work. In Python terms, you can place our library files in the **lib** directory because it's part of the Python path by default.
One downside of this approach of separate libraries is that they are not built in. To use them, one needs to copy them to the **CIRCUITPY** drive before they can be used. Fortunately, there is a library bundle.
The bundle and the library releases on GitHub also feature optimized versions of the libraries with the **.mpy** file extension. These files take less space on the drive and have a smaller memory footprint as they are loaded.
Due to the regular updates and space constraints, Adafruit does not ship boards with the entire bundle. Therefore, you will need to load the libraries you need when you begin working with your board. You can find example code in the guides for your board that depends on external libraries.
Either way, as you start to explore CircuitPython, you'll want to know how to get libraries on board.
# The Adafruit Learn Guide Project Bundle
The quickest and easiest way to get going with a project from the Adafruit Learn System is by utilising the Project Bundle. Most guides now have a **Download Project Bundle** button available at the top of the full code example embed. This button downloads all the necessary files, including images, etc., to get the guide project up and running. Simply click, open the resulting zip, copy over the right files, and you're good to go!
The first step is to find the Download Project Bundle button in the guide you're working on.
Info:
Warning:
The Download Project Bundle button downloads a zip file. This zip contains a series of directories, nested within which is the **code.py** , any applicable assets like images or audio, and the **lib/** folder containing all the necessary libraries. The following zip was downloaded from the Piano in the Key of Lime guide.
Info:
When you open the zip, you'll find some nested directories. Navigate through them until you find what you need. You'll eventually find a directory for your CircuitPython version (in this case, 7.x). In the version directory, you'll find the file and directory you need: **code.py** and **lib/**. Once you find the content you need, you can copy it all over to your **CIRCUITPY** drive, replacing any files already on the drive with the files from the freshly downloaded zip.
Info:
Once you copy over all the relevant files, the project should begin running! If you find that the project is not running as expected, make sure you've copied ALL of the project files onto your microcontroller board.
That's all there is to using the Project Bundle!
# The Adafruit CircuitPython Library Bundle
Adafruit provides CircuitPython libraries for much of the hardware they provide, including sensors, breakouts and more. To eliminate the need for searching for each library individually, the libraries are available together in the Adafruit CircuitPython Library Bundle. The bundle contains all the files needed to use each library.
## Downloading the Adafruit CircuitPython Library Bundle
You can download the latest Adafruit CircuitPython Library Bundle release by clicking the button below. The libraries are being constantly updated and improved, so you'll always want to download the latest bundle.
**Match up the bundle version with the version of CircuitPython you are running.** For example, you would download the 6.x library bundle if you're running any version of CircuitPython 6, or the 7.x library bundle if you're running any version of CircuitPython 7, etc. If you mix libraries with major CircuitPython versions, you will get incompatible mpy errors due to changes in library interfaces possible during major version changes.
[Click to visit circuitpython.org for the latest Adafruit CircuitPython Library Bundle](https://circuitpython.org/libraries)
**Download the bundle version that matches your CircuitPython firmware version.** If you don't know the version, check the version info in **boot\_out.txt** file on the **CIRCUITPY** drive, or the initial prompt in the CircuitPython REPL. For example, if you're running v7.0.0, download the 7.x library bundle.
There's also a **py** bundle which contains the uncompressed python files, you probably _don't_ want that unless you are doing advanced work on libraries.
# The CircuitPython Community Library Bundle
The CircuitPython Community Library Bundle is made up of libraries written and provided by members of the CircuitPython community. These libraries are often written when community members encountered hardware not supported in the Adafruit Bundle, or to support a personal project. The authors all chose to submit these libraries to the Community Bundle make them available to the community.
**These libraries are maintained by their authors and are not supported by Adafruit.** As you would with any library, if you run into problems, feel free to file an issue on the GitHub repo for the library. Bear in mind, though, that most of these libraries are supported by a single person and you should be patient about receiving a response. Remember, these folks are not paid by Adafruit, and are volunteering their personal time when possible to provide support.
## Downloading the CircuitPython Community Library Bundle
You can download the latest CircuitPython Community Library Bundle release by clicking the button below. The libraries are being constantly updated and improved, so you'll always want to download the latest bundle.
[Click for the latest CircuitPython Community Library Bundle release](https://github.com/adafruit/CircuitPython_Community_Bundle/releases)
The link takes you to the latest release of the CircuitPython Community Library Bundle on GitHub. There are multiple versions of the bundle available. **Download the bundle version that matches your CircuitPython firmware version.** If you don't know the version, check the version info in **boot\_out.txt** file on the **CIRCUITPY** drive, or the initial prompt in the CircuitPython REPL. For example, if you're running v7.0.0, download the 7.x library bundle.
# Understanding the Bundle
After downloading the zip, extract its contents. This is usually done by double clicking on the zip. On Mac OSX, it places the file in the same directory as the zip.
Open the bundle folder. Inside you'll find two information files, and two folders. One folder is the lib bundle, and the other folder is the examples bundle.
Now open the lib folder. When you open the folder, you'll see a large number of **.**** mpy** files, and folders.
## Example Files
All example files from each library are now included in the bundles in an **examples** directory (as seen above), as well as an examples-only bundle. These are included for two main reasons:
- Allow for quick testing of devices.
- Provide an example base of code, that is easily built upon for individualized purposes.
## Copying Libraries to Your Board
First open the **lib** folder on your **CIRCUITPY** drive. Then, open the **lib** folder you extracted from the downloaded zip. Inside you'll find a number of folders and **.mpy** files. Find the library you'd like to use, and copy it to the **lib** folder on **CIRCUITPY**.
If the library is a directory with multiple **.mpy** files in it, be sure to **copy the entire folder to CIRCUITPY/lib**.
This also applies to example files. Open the **examples** folder you extracted from the downloaded zip, and copy the applicable file to your **CIRCUITPY** drive. Then, rename it to **code.py** to run it.
Info:
# Understanding Which Libraries to Install
You now know how to load libraries on to your CircuitPython-compatible microcontroller board. You may now be wondering, how do you know _which_ libraries you need to install? Unfortunately, it's not always straightforward. Fortunately, there is an obvious place to start, and a relatively simple way to figure out the rest. First up: the best place to start.
When you look at most CircuitPython examples, you'll see they begin with one or more `import` statements. These typically look like the following:
- `import library_or_module`
However, `import` statements can also sometimes look like the following:
- `from library_or_module import name`
- `from library_or_module.subpackage import name`
- `from library_or_module import name as local_name`
They can also have more complicated formats, such as including a `try` / `except` block, etc.
The important thing to know is that **an** `import` **statement will always include the name of the module or library that you're importing**.
Therefore, the best place to start is by reading through the `import` statements.
Here is an example import list for you to work with in this section. There is no setup or other code shown here, as the purpose of this section involves only the import list.
```python
import time
import board
import neopixel
import adafruit_lis3dh
import usb_hid
from adafruit_hid.consumer_control import ConsumerControl
from adafruit_hid.consumer_control_code import ConsumerControlCode
```
Keep in mind, not all imported items are libraries. Some of them are almost always built-in CircuitPython modules. How do you know the difference? Time to visit the REPL.
In the [Interacting with the REPL section](https://learn.adafruit.com/welcome-to-circuitpython/the-repl#interacting-with-the-repl-2977486-14) on [The REPL page](https://learn.adafruit.com/welcome-to-circuitpython/the-repl) in this guide, the `help("modules")` command is discussed. This command provides a list of all of the built-in modules available in CircuitPython for your board. So, if you connect to the serial console on your board, and enter the REPL, you can run `help("modules")` to see what modules are available for your board. Then, as you read through the `import` statements, you can, for the purposes of figuring out which libraries to load, ignore the statement that import modules.
The following is the list of modules built into CircuitPython for the Feather RP2040. Your list may look similar or be anything down to a significant subset of this list for smaller boards.
Now that you know what you're looking for, it's time to read through the import statements. The first two, `time` and `board`, are on the modules list above, so they're built-in.
The next one, `neopixel`, is not on the module list. That means it's your first library! So, you would head over to the bundle zip you downloaded, and search for **neopixel**. There is a **neopixel.mpy** file in the bundle zip. Copy it over to the **lib** folder on your **CIRCUITPY** drive. The following one, `adafruit_lis3dh`, is also not on the module list. Follow the same process for **adafruit\_lis3dh** , where you'll find **adafruit\_lis3dh.mpy** , and copy that over.
The fifth one is `usb_hid`, and it is in the modules list, so it is built in. Often all of the built-in modules come first in the import list, but sometimes they don't! Don't assume that everything after the first library is also a library, and verify each import with the modules list to be sure. Otherwise, you'll search the bundle and come up empty!
The final two imports are not as clear. Remember, when `import` statements are formatted like this, the first thing after the `from` is the library name. In this case, the library name is `adafruit_hid`. A search of the bundle will find an **adafruit\_hid _folder_**. When a library is a folder, you must copy the **entire folder and its contents _as it is in the bundle_** to the **lib** folder on your **CIRCUITPY** drive. In this case, you would copy the entire **adafruit\_hid** folder to your **CIRCUITPY/lib** folder.
Notice that there are _two_ imports that begin with `adafruit_hid`. Sometimes you will need to import more than one thing from the same library. Regardless of how many times you import the same library, you only need to load the library by copying over the **adafruit\_hid** folder _once_.
That is how you can use your example code to figure out what libraries to load on your CircuitPython-compatible board!
There are cases, however, where libraries require other libraries internally. The internally required library is called a _dependency_. In the event of library dependencies, the easiest way to figure out what other libraries are required is to connect to the serial console and follow along with the `ImportError` printed there. The following is a very simple example of an `ImportError`, but the concept is the same for any missing library.
# Example: `ImportError` Due to Missing Library
If you choose to load libraries as you need them, or you're starting fresh with an existing example, you may end up with code that tries to use a library you haven't yet loaded. This section will demonstrate what happens when you try to utilise a library that you don't have loaded on your board, and cover the steps required to resolve the issue.
This demonstration will only return an error if you do not have the required library loaded into the **lib** folder on your **CIRCUITPY** drive **.**
Let's use a modified version of the Blink example.
```auto
import board
import time
import simpleio
led = simpleio.DigitalOut(board.LED)
while True:
led.value = True
time.sleep(0.5)
led.value = False
time.sleep(0.5)
```
Save this file. Nothing happens to your board. Let's check the serial console to see what's going on.
You have an `ImportError`. It says there is `no module named 'simpleio'`. That's the one you just included in your code!
Click the link above to download the correct bundle. Extract the lib folder from the downloaded bundle file. Scroll down to find **simpleio.mpy**. This is the library file you're looking for! Follow the steps above to load an individual library file.
The LED starts blinking again! Let's check the serial console.
No errors! Excellent. You've successfully resolved an `ImportError`!
If you run into this error in the future, follow along with the steps above and choose the library that matches the one you're missing.
# Library Install on Non-Express Boards
If you have an M0 non-Express board such as Trinket M0, Gemma M0, QT Py M0, or one of the M0 Trinkeys, you'll want to follow the same steps in the example above to install libraries as you need them. Remember, you don't need to wait for an `ImportError` if you know what library you added to your code. Open the library bundle you downloaded, find the library you need, and drag it to the **lib** folder on your **CIRCUITPY** drive.
You can still end up running out of space on your M0 non-Express board even if you only load libraries as you need them. There are a number of steps you can use to try to resolve this issue. You'll find suggestions on the [Troubleshooting page](https://learn.adafruit.com/welcome-to-circuitpython/troubleshooting).
# Updating CircuitPython Libraries and Examples
Libraries and examples are updated from time to time, and it's important to update the files you have on your **CIRCUITPY** drive.
To update a single library or example, follow the same steps above. When you drag the library file to your lib folder, it will ask if you want to replace it. Say yes. That's it!
A new library bundle is released every time there's an update to a library. Updates include things like bug fixes and new features. It's important to check in every so often to see if the libraries you're using have been updated.
## CircUp CLI Tool
There is a command line interface (CLI) utility called [CircUp](https://learn.adafruit.com/keep-your-circuitpython-libraries-on-devices-up-to-date-with-circup) that can be used to easily install and update libraries on your device. Follow the directions on the [install page within the CircUp learn guide](https://learn.adafruit.com/keep-your-circuitpython-libraries-on-devices-up-to-date-with-circup/install-circup). Once you've got it installed you run the command `circup update` in a terminal to interactively update all libraries on the connected CircuitPython device. See the [usage page in the CircUp guide](https://learn.adafruit.com/keep-your-circuitpython-libraries-on-devices-up-to-date-with-circup/usage) for a full list of functionality
# Adafruit Circuit Playground Bluefruit
## Frequently Asked Questions
These are some of the common questions regarding CircuitPython and CircuitPython microcontrollers.
###
What are some common acronyms to know?
CP or CPy = [CircuitPython](https://circuitpython.org)
CPC = [Circuit Playground Classic](https://www.adafruit.com/product/3000) (does not run CircuitPython)
CPX = [Circuit Playground Express](https://www.adafruit.com/product/3333)
CPB = [Circuit Playground Bluefruit](https://www.adafruit.com/product/4333)
## Using Older Versions
Danger:
### I have to continue using CircuitPython 8.x or earlier. Where can I find compatible libraries?
**We are no longer building or supporting the CircuitPython 8.x or earlier library bundles. We highly encourage you to [update CircuitPython to the latest version](https://circuitpython.org/downloads) and use [the current version of the libraries](https://circuitpython.org/libraries).** However, if for some reason you cannot update, here are the last available library bundles for older versions:
- [2.x bundle](https://github.com/adafruit/Adafruit_CircuitPython_Bundle/releases/download/20190903/adafruit-circuitpython-bundle-2.x-mpy-20190903.zip)
- [3.x bundle](https://github.com/adafruit/Adafruit_CircuitPython_Bundle/releases/download/20190903/adafruit-circuitpython-bundle-3.x-mpy-20190903.zip)
- [4.x bundle](https://github.com/adafruit/Adafruit_CircuitPython_Bundle/releases/download/20200707/adafruit-circuitpython-bundle-4.x-mpy-20200707.zip)
- [5.x bundle](https://github.com/adafruit/Adafruit_CircuitPython_Bundle/releases/download/20210129/adafruit-circuitpython-bundle-5.x-mpy-20210129.zip)
- [6.x bundle](https://github.com/adafruit/Adafruit_CircuitPython_Bundle/releases/download/20211213/adafruit-circuitpython-bundle-6.x-mpy-20211213.zip)
- [7.x bundle](https://github.com/adafruit/Adafruit_CircuitPython_Bundle/releases/download/20231003/adafruit-circuitpython-bundle-7.x-mpy-20231003.zip)
- [8.x bundle](https://github.com/adafruit/Adafruit_CircuitPython_Bundle/releases/download/20250213/adafruit-circuitpython-bundle-8.x-mpy-20250213.zip)
## Python Arithmetic
###
Does CircuitPython support floating-point numbers?
All CircuitPython boards support floating point arithmetic, even if the microcontroller chip does not support floating point in hardware. Floating point numbers are stored in 30 bits, with an 8-bit exponent and a 22-bit mantissa. Note that this is two bits less than standard 32-bit single-precision floats. You will get about 5-1/2 digits of decimal precision.
(The **broadcom** port may provide 64-bit floats in some cases.)
###
Does CircuitPython support long integers, like regular Python?
Python long integers (integers of arbitrary size) are available on most builds, except those on boards with the smallest available firmware size. On these boards, integers are stored in 31 bits.
Boards without long integer support are mostly SAMD21 ("M0") boards without an external flash chip, such as the Adafruit Gemma M0, Trinket M0, QT Py M0, and the Trinkey series. There are also a number of third-party boards in this category. There are also a few small STM third-party boards without long integer support.
`time.localtime()`, `time.mktime()`, `time.time()`, and `time.monotonic_ns()` are available only on builds with long integers.
## Wireless Connectivity
###
How do I connect to the Internet with CircuitPython?
If you'd like to include WiFi in your project, your best bet is to use a board that is running natively on ESP32 chipsets - those have WiFi built in!
If your development board has an SPI port and at least 4 additional pins, you can check out [this guide](https://learn.adafruit.com/adafruit-io-basics-airlift) on using AirLift with CircuitPython - extra wiring is required and some boards like the MacroPad or NeoTrellis do not have enough available pins to add the hardware support.
For further project examples, and guides about using AirLift with specific hardware, check out [the Adafruit Learn System](https://learn.adafruit.com/search?q=airlift).
### How do I do BLE (Bluetooth Low Energy) with CircuitPython?
nRF52840, nRF52833, and **as of CircuitPython 9.1.0** , ESP32, ESP32-C3, and ESP32-S3 boards (with 8MB) have the most complete BLE implementation. Your program can act as both a BLE central and peripheral. As a central, you can scan for advertisements, and connect to an advertising board. As a peripheral, you can advertise, and you can create services available to a central. Pairing and bonding are supported.
**Most Espressif boards with only 4MB of flash do not have enough room to include BLE in CircuitPython 9.** Check the [Module Support Matrix](https://docs.circuitpython.org/en/latest/shared-bindings/support_matrix.html) to see if your board has support for `_bleio`. CircuitPython 10 is planned to support `_bleio` on Espressif boards with 4MB flash.
Note that the ESP32-S2 does not have Bluetooth capability.
On most other boards with adequate firmware space, [BLE is available for use with AirLift](https://learn.adafruit.com/adafruit-airlift-breakout/circuitpython-ble) or other NINA-FW-based co-processors. Some boards have this coprocessor on board, such as the [PyPortal](https://learn.adafruit.com/adafruit-pyportal/circuitpython-ble). Currently, this implementation only supports acting as a BLE peripheral. Scanning and connecting as a central are not yet implemented. Bonding and pairing are not supported.
###
Are there other ways to communicate by radio with CircuitPython?
Check out [Adafruit's RFM boards](https://www.adafruit.com/?q=rfm&sort=BestMatch)for simple radio communication supported by CircuitPython, which can be used over distances of 100m to over a km, depending on the version. The RFM SAMD21 M0 boards can be used, but they were not designed for CircuitPython, and have limited RAM and flash space; using the RFM breakouts or FeatherWings with more capable boards will be easier.
## Asyncio and Interrupts
###
Is there asyncio support in CircuitPython?
There is support for asyncio starting with CircuitPython 7.1.0, on all boards except the smallest SAMD21 builds. Read about using it in the [Cooperative Multitasking in CircuitPython](https://learn.adafruit.com/cooperative-multitasking-in-circuitpython) Guide.
###
Does CircuitPython support interrupts?
No. CircuitPython does not currently support interrupts - please use asyncio for multitasking / 'threaded' control of your code
## Status RGB LED
###
My RGB NeoPixel/DotStar LED is blinking funny colors - what does it mean?
The status LED can tell you what's going on with your CircuitPython board. [Read more here for what the colors mean!](https://learn.adafruit.com/welcome-to-circuitpython/troubleshooting#circuitpython-rgb-status-light-2978455-24)
## Memory Issues
###
What is a MemoryError?
Memory allocation errors happen when you're trying to store too much on the board. The CircuitPython microcontroller boards have a limited amount of memory available. You can have about 250 lines of code on the M0 Express boards. If you try to `import` too many libraries, a combination of large libraries, or run a program with too many lines of code, your code will fail to run and you will receive a `MemoryError` in the serial console.
###
What do I do when I encounter a MemoryError?
Try resetting your board. Each time you reset the board, it reallocates the memory. While this is unlikely to resolve your issue, it's a simple step and is worth trying.
Make sure you are using **.mpy** versions of libraries. All of the CircuitPython libraries are available in the bundle in a **.mpy** format which takes up less memory than **.py** format. Be sure that you're using [the latest library bundle](https://github.com/adafruit/Adafruit_CircuitPython_Bundle/releases) for your version of CircuitPython.
If that does not resolve your issue, try shortening your code. Shorten comments, remove extraneous or unneeded code, or any other clean up you can do to shorten your code. If you're using a lot of functions, you could try moving those into a separate library, creating a **.mpy** of that library, and importing it into your code.
You can turn your entire file into a **.mpy** and `import` that into **code.py**. This means you will be unable to edit your code live on the board, but it can save you space.
###
Can the order of my .mpy files?
You can make your own **.mpy** versions of files with `mpy-cross`.
You can download **mpy-cross** for your operating system from [here](https://adafruit-circuit-python.s3.amazonaws.com/index.html?prefix=bin/mpy-cross/). Builds are available for Windows, macOS, x64 Linux, and Raspberry Pi Linux. Choose the latest **mpy-cross** whose version matches the version of CircuitPython you are using.
On macOS and Linux, after you download **mpy-cross** , you must make the the file executable by doing `chmod +x name-of-the-mpy-cross-executable`.
To make a **.mpy** file, run `./mpy-cross path/to/yourfile.py` to create a **yourfile.mpy** in the same directory as the original file.
###
How do I check how much memory I have free?
Run the following to see the number of bytes available for use:
`import gc`
`gc.mem_free()`
## Unsupported Hardware
###
Is ESP8266 or ESP32 supported in CircuitPython? Why not?
We dropped ESP8266 support as of 4.x - For more information please read about it [here](https://learn.adafruit.com/welcome-to-circuitpython/circuitpython-for-esp8266)!
[As of CircuitPython 8.x we have started to support ESP32 and ESP32-C3 and have added a WiFi workflow for wireless coding!](https://learn.adafruit.com/circuitpython-with-esp32-quick-start)
We also support ESP32-S2 & ESP32-S3, which have native USB.
###
Does Feather M0 support WINC1500?
No, WINC1500 will not fit into the M0 flash space.
###
Can AVRs such as ATmega328 or ATmega2560 run CircuitPython?
No.
# Adafruit Circuit Playground Bluefruit
## CircuitPython Expectations
Danger:
# Always Run the Latest Version of CircuitPython and Libraries
As we continue to develop CircuitPython and create new releases, we will stop supporting older releases. **You need to [update to the latest CircuitPython](https://circuitpython.org/downloads).**
You need to download the CircuitPython Library Bundle that matches your version of CircuitPython. **Please update CircuitPython and then [download the latest bundle](https://circuitpython.org/libraries)**.
As we release new versions of CircuitPython, we will stop providing the previous bundles as automatically created downloads on the Adafruit CircuitPython Library Bundle repo. If you must continue to use an earlier version, you can still download the appropriate version of `mpy-cross` from the particular release of CircuitPython on the CircuitPython repo and create your own compatible .mpy library files. **However, it is best to update to the latest for both CircuitPython and the library bundle.**
# I have to continue using CircuitPython 3.x or 2.x, where can I find compatible libraries?
**We are no longer building or supporting the CircuitPython 2.x and 3.x library bundles. We highly encourage you to [update CircuitPython to the latest version](https://circuitpython.org/downloads) and use [the current version of the libraries](https://circuitpython.org/libraries).** However, if for some reason you cannot update, you can find [the last available 2.x build here](https://github.com/adafruit/Adafruit_CircuitPython_Bundle/releases/download/20190903/adafruit-circuitpython-bundle-2.x-mpy-20190903.zip) and [the last available 3.x build here](https://github.com/adafruit/Adafruit_CircuitPython_Bundle/releases/download/20190903/adafruit-circuitpython-bundle-3.x-mpy-20190903.zip).
# Switching Between CircuitPython and Arduino
Many of the CircuitPython boards also run Arduino. But how do you switch between the two? Switching between CircuitPython and Arduino is easy.
If you're currently running Arduino and would like to start using CircuitPython, follow the steps found in [Welcome to CircuitPython: Installing CircuitPython](https://learn.adafruit.com/welcome-to-circuitpython/installing-circuitpython).
If you're currently running CircuitPython and would like to start using Arduino, plug in your board, and then load your Arduino sketch. If there are any issues, you can double tap the reset button to get into the bootloader and then try loading your sketch. Always backup any files you're using with CircuitPython that you want to save as they could be deleted.
That's it! It's super simple to switch between the two.
# The Difference Between Express And Non-Express Boards
We often reference "Express" and "Non-Express" boards when discussing CircuitPython. What does this mean?
Express refers to the inclusion of an extra 2MB flash chip on the board that provides you with extra space for CircuitPython and your code. This means that we're able to include more functionality in CircuitPython and you're able to do more with your code on an Express board than you would on a non-Express board.
Express boards include Circuit Playground Express, ItsyBitsy M0 Express, Feather M0 Express, Metro M0 Express and Metro M4 Express.
Non-Express boards include Trinket M0, Gemma M0, QT Py, Feather M0 Basic, and other non-Express Feather M0 variants.
# Non-Express Boards: Gemma, Trinket, and QT Py
CircuitPython runs nicely on the Gemma M0, Trinket M0, or QT Py M0 but there are some constraints
### Small Disk Space
Since we use the internal flash for disk, and that's shared with runtime code, its limited! Only about 50KB of space.
### No Audio or NVM
Part of giving up that FLASH for disk means we couldn't fit everything in. There is, at this time, no support for hardware audio playpack or NVM 'eeprom'. Modules `audioio` and `bitbangio` are not included. For that support, check out the Circuit Playground Express or other Express boards.
However, I2C, UART, capacitive touch, NeoPixel, DotStar, PWM, analog in and out, digital IO, logging storage, and HID do work! Check the CircuitPython Essentials for examples of all of these.
# Differences Between CircuitPython and MicroPython
For the differences between CircuitPython and MicroPython, check out the [CircuitPython documentation](https://circuitpython.readthedocs.io/en/latest/README.html#differences-from-micropython).
# Differences Between CircuitPython and Python
Python (also known as CPython) is the language that MicroPython and CircuitPython are based on. There are many similarities, but there are also many differences. This is a list of a few of the differences.
### Python Libraries
Python is advertised as having "batteries included", meaning that many standard libraries are included. Unfortunately, for space reasons, many Python libraries are not available. So for instance while we wish you could `import numpy`, `numpy` isn't available (look for the `ulab` library for similar functions to `numpy` which works on many microcontroller boards). So you may have to port some code over yourself!
### Integers in CircuitPython
On the non-Express boards, integers can only be up to 31 bits long. Integers of unlimited size are not supported. The largest positive integer that can be represented is 230-1, 1073741823, and the most negative integer possible is -230, -1073741824.
As of CircuitPython 3.0, Express boards have arbitrarily long integers as in Python.
### Floating Point Numbers and Digits of Precision for Floats in CircuitPython
Floating point numbers are single precision in CircuitPython (not double precision as in Python). The largest floating point magnitude that can be represented is about +/-3.4e38. The smallest magnitude that can be represented with full accuracy is about +/-1.7e-38, though numbers as small as +/-5.6e-45 can be represented with reduced accuracy.
CircuitPython's floats have 8 bits of exponent and 22 bits of mantissa (not 24 like regular single precision floating point), which is about five or six decimal digits of precision.
### Differences between MicroPython and Python
For a more detailed list of the differences between CircuitPython and Python, you can look at the MicroPython documentation. [We keep up with MicroPython stable releases, so check out the core 'differences' they document here.](http://docs.micropython.org/en/latest/pyboard/genrst/index.html)
# Adafruit Circuit Playground Bluefruit
## Troubleshooting
From time to time, you will run into issues when working with CircuitPython. Here are a few things you may encounter and how to resolve them.
Danger:
# Always Run the Latest Version of CircuitPython and Libraries
As CircuitPython development continues and there are new releases, Adafruit will stop supporting older releases. **You need to [update to the latest CircuitPython.](https://circuitpython.org/downloads).**
You need to download the CircuitPython Library Bundle that matches your version of CircuitPython. **Please update CircuitPython and then [download the latest bundle](https://circuitpython.org/libraries)**.
As new versions of CircuitPython are released, Adafruit will stop providing the previous bundles as automatically created downloads on the Adafruit CircuitPython Library Bundle repo. If you must continue to use an earlier version, you can still download the appropriate version of `mpy-cross` from the particular release of CircuitPython on the CircuitPython repo and create your own compatible .mpy library files. **However, it is best to update to the latest for both CircuitPython and the library bundle.**
## I have to continue using CircuitPython 7.x or earlier. Where can I find compatible libraries?
**Adafruit is no longer building or supporting the CircuitPython 7.x or earlier library bundles. You are highly encourged to [update CircuitPython to the latest version](https://circuitpython.org/downloads) and use [the current version of the libraries](https://circuitpython.org/libraries).** However, if for some reason you cannot update, links to the previous bundles are available in the [FAQ](https://learn.adafruit.com/welcome-to-circuitpython/frequently-asked-questions#faq-3105289).
# macOS Sonoma before 14.4: Errors Writing to CIRCUITPY macOS 14.4 - 15.1: Slow Writes to CIRCUITPY
macOS Sonoma before 14.4 took many seconds to complete writes to small FAT drives, 8MB or smaller. This causes errors when writing to CIRCUITPY. The best solution was to remount the CIRCUITPY drive after it is automatically mounted. Or consider downgrading back to Ventura if that works for you. This problem was tracked in [CircuitPython GitHub issue 8449](https://github.com/adafruit/circuitpython/issues/8449).
Below is a shell script to do this remount conveniently (courtesy [@czei in GitHub](https://github.com/adafruit/circuitpython/issues/8449#issuecomment-1779981373)). Copy the code here into a file named, say, **remount-CIRCUITPY.sh**. Place the file in a directory on your PATH, or in some other convenient place.
macOS Sonoma 14.4 and versions of macOS before Sequoia 15.2 did not have the problem above, but did take an inordinately long time to write to FAT drives of size 1GB or less (40 times longer than 2GB drives). As of macOS 15.2, writes are no longer very slow. This problem was tracked in [CircuitPython GitHub issue 8918](https://github.com/adafruit/circuitpython/issues/8918).
```auto
#!/bin/sh
#
# This works around bug where, by default,
# macOS 14.x before 14.4 writes part of a file immediately,
# and then doesn't update the directory for 20-60 seconds, causing
# the file system to be corrupted.
#
disky=`df | grep CIRCUITPY | cut -d" " -f1`
sudo umount /Volumes/CIRCUITPY
sudo mkdir /Volumes/CIRCUITPY
sleep 2
sudo mount -v -o noasync -t msdos $disky /Volumes/CIRCUITPY
```
Then in a Terminal window, do this to make this script executable:
```terminal
chmod +x remount-CIRCUITPY.sh
```
Place the file in a directory on your `PATH`, or in some other convenient place.
Now, each time you plug in or reset your CIRCUITPY board, run the file **remount-CIRCUITPY.sh**. You can run it in a Terminal window or you may be able to place it on the desktop or in your dock to run it just by double-clicking.
This will be something of a nuisance but it is the safest solution.
This problem is being tracked in [this CircuitPython issue](https://github.com/adafruit/circuitpython/issues/8449).
# Bootloader (_boardname_BOOT) Drive Not Present
### **You may have a different board.**
Only Adafruit Express boards and the SAMD21 non-Express boards ship with the [UF2 bootloader](../../../adafruit-feather-m0-express-designed-for-circuit-python-circuitpython/uf2-bootloader?view=all#uf2-bootloader)installed. The Feather M0 Basic, Feather M0 Adalogger, and similar boards use a regular Arduino-compatible bootloader, which does not show a **_boardname_BOOT** drive.
### **MakeCode**
If you are running a [MakeCode](../../../makecode/sharing-and-saving?view=all#step-1-bootloader-mode) program on Circuit Playground Express, press the reset button just once to get the **CPLAYBOOT** drive to show up. Pressing it twice will not work.
### **macOS**
**DriveDx** and its accompanything **SAT SMART Driver** can interfere with seeing the BOOT drive. [See this forum post](https://forums.adafruit.com/viewtopic.php?f=58&t=161917&p=799309#p799215) for how to fix the problem.
### **Windows 10 or later**
Did you install the Adafruit Windows Drivers package by mistake, or did you upgrade to Windows 10 or later with the driver package installed? You don't need to install this package on Windows 10 or 11for most Adafruit boards. The old version (v1.5) can interfere with recognizing your device. Go to **Settings** -\> **Apps** and uninstall all the "Adafruit" driver programs.
### **Windows 7 or 8.1**
Windows 7 and 8.1 have reached end of life. It is [recommended](https://learn.adafruit.com/welcome-to-circuitpython/installing-circuitpython#windows-7-and-8-dot-1-drivers-2977910-9) that you upgrade to Windows 10 or 11 if possible. Drivers are available for some older CircuitPython boards, but there are no plans to release drivers for newer boards.
Info: The Windows Drivers installer was last updated in November 2020 (v2.5.0.0) . Windows 7 drivers for CircuitPython boards released since then, including RP2040 boards, are not available. There are no plans to release drivers for newer boards. The boards work fine on Windows 10 and later.
You should now be done! Test by unplugging and replugging the board. You should see the **CIRCUITPY** drive, and when you double-click the reset button (single click on Circuit Playground Express running MakeCode), you should see the appropriate **_boardname_BOOT** drive.
Let us know in the [Adafruit support forums](https://forums.adafruit.com) or on the [Adafruit Discord](https://adafru.it/discord) if this does not work for you!
# Windows Explorer Locks Up When Accessing **_boardname_BOOT** Drive
On Windows, several third-party programs that can cause issues. The symptom is that you try to access the **_boardname_BOOT** drive, and Windows or Windows Explorer seems to lock up. These programs are known to cause trouble:
- **AIDA64** : to fix, stop the program. This problem has been reported to AIDA64. They acquired hardware to test, and released a beta version that fixes the problem. This may have been incorporated into the latest release. Please let us know in the forums if you test this.
- **BitDefender anti-virus**
- **Hard Disk Sentinel**
- **Kaspersky anti-virus** : To fix, you may need to disable Kaspersky completely. Disabling some aspects of Kaspersky does not always solve the problem. This problem has been reported to Kaspersky.
- **ESET NOD32 anti-virus** : There have been problems with at least version 9.0.386.0, solved by uninstallation.
# Copying UF2 to **_boardname_BOOT** Drive Hangs at 0% Copied
On Windows, a **Western DIgital (WD) utility** that comes with their external USB drives can interfere with copying UF2 files to the **_boardname_BOOT** drive. Uninstall that utility to fix the problem.
# CIRCUITPY Drive Does Not Appear or Disappears Quickly
**BitDefender anti-virus has been reported to block access to** **CIRCUITPY**. You can set an exception for the drive letter.
Kaspersky **anti-virus** can block the appearance of the **CIRCUITPY** drive. There has not yet been settings change discovered that prevents this. Complete uninstallation of Kaspersky fixes the problem.
**Norton anti-virus** can interfere with **CIRCUITPY**. A user has reported this problem on Windows 7. The user turned off both Smart Firewall and Auto Protect, and **CIRCUITPY** then appeared.
**Sophos Endpoint** security software [can cause CIRCUITPY to disappear](https://forums.adafruit.com/viewtopic.php?f=60&t=187629) and the BOOT drive to reappear. It is not clear what causes this behavior.
**Samsung Magician** can cause CIRCUITPY to disappear (reported [here](https://forums.adafruit.com/viewtopic.php?t=205159) and [here](https://forums.adafruit.com/viewtopic.php?p=987596#p987596)).
## "M105" Seen on Display, Crashes, Missing CIRCUITPY
The **Cura** 3D printing program sends 3D printing GCODE commands to unused serial ports to try to find 3D printers connected over serial. This causes a variety of problems. Disable (uncheck) **USB Printing** in Cura in the **Market** -\> **Installed** menu, or uninstall Cura. For more information see [this forum post](https://forums.adafruit.com/viewtopic.php?t=192784), [this CircuitPython issue](https://github.com/adafruit/circuitpython/issues/2585), and [this Cura issue](https://github.com/Ultimaker/Cura/issues/5207).
# Device Errors or Problems on Windows
Windows can become confused about USB device installations. Try cleaning up your USB devices. Use [Uwe Sieber's Device Cleanup Tool](https://www.uwe-sieber.de/misc_tools_e.html) (on that page, scroll down to "Device Cleanup Tool"). Download and unzip the tool. Unplug all the boards and other USB devices you want to clean up. Run the tool as Administrator. You will see a listing like this, probably with many more devices. It is listing all the USB devices that are _not_ currently attached.
Select all the devices you want to remove, and then press Delete. It is usually safe just to select everything. Any device that is removed will get a fresh install when you plug it in. Using the Device Cleanup Tool also discards all the COM port assignments for the unplugged boards. If you have used many Arduino and CircuitPython boards, you have probably seen higher and higher COM port numbers used, seemingly without end. This will fix that problem.
# Serial Console in Mu Not Displaying Anything
There are times when the serial console will accurately not display anything, such as, when no code is currently running, or when code with no serial output is already running before you open the console. However, if you find yourself in a situation where you feel it should be displaying something like an error, consider the following.
Depending on the size of your screen or Mu window, when you open the serial console, the serial console panel may be very small. This can be a problem. A basic CircuitPython error takes 10 lines to display!
```
Auto-reload is on. Simply save files over USB to run them or enter REPL to disable.
code.py output:
Traceback (most recent call last):
File "code.py", line 7
SyntaxError: invalid syntax
Press any key to enter the REPL. Use CTRL-D to reload.
```
More complex errors take even more lines!
Therefore, if your serial console panel is five lines tall or less, you may only see blank lines or blank lines followed by `Press any key to enter the REPL. Use CTRL-D to reload.`. If this is the case, you need to either mouse over the top of the panel to utilise the option to resize the serial panel, or use the scrollbar on the right side to scroll up and find your message.
This applies to any kind of serial output whether it be error messages or print statements. So before you start trying to debug your problem on the hardware side, be sure to check that you haven't simply missed the serial messages due to serial output panel height.
# code.py Restarts Constantly
CircuitPython will restart **code.py** if you or your computer writes to something on the CIRCUITPY drive. This feature is called _auto-reload_, and lets you test a change to your program immediately.
Some utility programs, such as backup, anti-virus, or disk-checking apps, will write to the CIRCUITPY as part of their operation. Sometimes they do this very frequently, causing constant restarts.
**Acronis True Image** and related Acronis programs on Windows are known to cause this problem. It is possible to prevent this by [disabling the "](https://forum.acronis.com/forum/acronis-true-image-2018-forum/acronis-ati-2018-contantly-touch-usb-port-causing-issue-adafruit-circuitpython-folder)[Acronis Managed Machine Service Mini"](https://forum.acronis.com/forum/acronis-true-image-2018-forum/acronis-ati-2018-contantly-touch-usb-port-causing-issue-adafruit-circuitpython-folder).
If you cannot stop whatever is causing the writes, you can disable auto-reload by putting this code in **boot.py** or **code.py** :
```python
import supervisor
supervisor.runtime.autoreload = False
```
# CircuitPython RGB Status Light
Nearly all CircuitPython-capable boards have a single NeoPixel or DotStar RGB LED on the board that indicates the status of CircuitPython. A few boards designed before CircuitPython existed, such as the Feather M0 Basic, do not.
**Circuit Playground Express and Circuit Playground Bluefruit have multiple RGB LEDs, but do NOT have a status LED. The LEDs are all green when in the bootloader. In versions before 7.0.0, they do NOT indicate any status while running CircuitPython.**
## **CircuitPython 7.0.0 and Later**
The status LED blinks were changed in CircuitPython 7.0.0 in order to save battery power and simplify the blinks. These blink patterns will occur on single color LEDs when the board does not have any RGB LEDs. Speed and blink count also vary for this reason.
On start up, the LED will blink **YELLOW** multiple times for 1 second. Pressing the RESET button (or on Espressif, the BOOT button) during this time will restart the board and then enter safe mode. On Bluetooth capable boards, after the yellow blinks, there will be a set of faster blue blinks. Pressing reset during the **BLUE** blinks will clear Bluetooth information and start the device in discoverable mode, so it can be used with a BLE code editor.
Once started, CircuitPython will blink a pattern every 5 seconds when no user code is running to indicate why the code stopped:
- 1 **GREEN** blink: Code finished without error.
- 2 **RED** blinks: Code ended due to an exception. Check the serial console for details.
- 3 **YELLOW** blinks: CircuitPython is in safe mode. No user code was run. Check the serial console for safe mode reason.
When in the REPL, CircuitPython will set the status LED to **WHITE**. You can change the LED color from the REPL. The status indicator will not persist on non-NeoPixel or DotStar LEDs.
## **CircuitPython 6.3.0 and earlier**
Here's what the colors and blinking mean:
- steady **GREEN** : **code.py** (or **code.txt** , **main.py** , or **main.txt** ) is running
- pulsing **GREEN** : **code.py** (etc.) has finished or does not exist
- steady **YELLOW** at start up: (4.0.0-alpha.5 and newer) CircuitPython is waiting for a reset to indicate that it should start in safe mode
- pulsing **YELLOW** : Circuit Python is in safe mode: it crashed and restarted
- steady **WHITE** : REPL is running
- steady **BLUE** : **boot.py** is running
Colors with multiple flashes following indicate a Python exception and then indicate the line number of the error. The color of the first flash indicates the type of error:
- **GREEN** : IndentationError
- **CYAN** : SyntaxError
- **WHITE** : NameError
- **ORANGE** : OSError
- **PURPLE** : ValueError
- **YELLOW** : other error
These are followed by flashes indicating the line number, including place value. **WHITE** flashes are thousands' place, **BLUE** are hundreds' place, **YELLOW** are tens' place, and **CYAN** are one's place. So for example, an error on line 32 would flash **YELLOW** three times and then **CYAN** two times. Zeroes are indicated by an extra-long dark gap.
# Serial console showing `ValueError: Incompatible .mpy file`
This error occurs when importing a module that is stored as a **.mpy** binary file that was generated by a different version of CircuitPython than the one its being loaded into. In particular, the mpy binary format changed between CircuitPython versions 6.x and 7.x, 2.x and 3.x, and 1.x and 2.x.
So, for instance, if you upgraded to CircuitPython 7.x from 6.x you’ll need to download a newer version of the library that triggered the error on `import`. All libraries are available in the [Adafruit bundle](https://github.com/adafruit/Adafruit_CircuitPython_Bundle/releases/latest).
# CIRCUITPY Drive Issues
You may find that you can no longer save files to your **CIRCUITPY** drive. You may find that your **CIRCUITPY** stops showing up in your file explorer, or shows up as **NO\_NAME**. These are indicators that your filesystem has issues. When the **CIRCUITPY** disk is not safely ejected before being reset by the button or being disconnected from USB, it may corrupt the flash drive. It can happen on Windows, Mac or Linux, though it is more common on Windows.
Be aware, if you have used Arduino to program your board, CircuitPython is no longer able to provide the USB services. You will need to reload CircuitPython to resolve this situation.
The easiest first step is to reload CircuitPython. Double-tap reset on the board so you get a **_boardname_BOOT** drive rather than a **CIRCUITPY** drive, and copy the latest version of CircuitPython ( **.uf2** ) back to the board. This may restore **CIRCUITPY** functionality.
If reloading CircuitPython does not resolve your issue, the next step is to try putting the board into safe mode.
## Safe Mode
Whether you've run into a situation where you can no longer edit your **code.py** on your **CIRCUITPY** drive, your board has gotten into a state where **CIRCUITPY** is read-only, or you have turned off the **CIRCUITPY** drive altogether, safe mode can help.
**Safe mode** in CircuitPython does not run any user code on startup, and disables auto-reload. This means a few things. First, safe mode _bypasses any code in_ **boot.py** (where you can set **CIRCUITPY** read-only or turn it off completely). Second, _it does not run the code in_ **code.py**. And finally, _it does not automatically soft-reload when data is written to the_ **CIRCUITPY** _drive_.
Therefore, whatever you may have done to put your board in a non-interactive state, safe mode gives you the opportunity to correct it without losing all of the data on the **CIRCUITPY** drive.
### Entering Safe Mode in CircuitPython 7.x and Later
You can enter safe by pressing reset during the right time when the board boots. Immediately after the board starts up or resets, it waits one second. On some boards, the onboard status LED will blink yellow during that time. If you press reset during that one second period, the board will start up in safe mode. It can be difficult to react to the yellow LED, so you may want to think of it simply as a "slow" double click of the reset button. (Remember, a fast double click of reset enters the bootloader.)
### Entering Safe Mode in CircuitPython 6.x
You can enter safe by pressing reset during the right time when the board boots.. Immediately after the board starts up or resets, it waits 0.7 seconds. On some boards, the onboard status LED (highlighted in green above) will turn solid yellow during this time. If you press reset during that 0.7 seconds, the board will start up in safe mode. It can be difficult to react to the yellow LED, so you may want to think of it simply as a slow double click of the reset button. (Remember, a fast double click of reset enters the bootloader.)
### In Safe Mode
Once you've entered safe mode successfully in CircuitPython 6.x, the LED will pulse yellow.
If you successfully enter safe mode on CircuitPython 7.x, the LED will intermittently blink yellow three times.
If you connect to the serial console, you'll find the following message.
```terminal
Auto-reload is off.
Running in safe mode! Not running saved code.
CircuitPython is in safe mode because you pressed the reset button during boot. Press again to exit safe mode.
Press any key to enter the REPL. Use CTRL-D to reload.
```
You can now edit the contents of the **CIRCUITPY** drive. Remember, _your code will not run until you press the reset button, or unplug and plug in your board, to get out of safe mode._
At this point, you'll want to remove any user code in **code.py** and, if present, the **boot.py** file from **CIRCUITPY**. Once removed, tap the reset button, or unplug and plug in your board, to restart CircuitPython. This will restart the board and may resolve your drive issues. If resolved, you can begin coding again as usual.
If safe mode does not resolve your issue, the board must be completely erased and CircuitPython must be reloaded onto the board.
Danger:
## To erase CIRCUITPY: `storage.erase_filesystem()`
CircuitPython includes a built-in function to erase and reformat the filesystem. If you have a version of CircuitPython older than 2.3.0 on your board, you can [update to the newest version](../../../../welcome-to-circuitpython/installing-circuitpython) to do this.
1. [Connect to the CircuitPython REPL](../../../../welcome-to-circuitpython/kattni-connecting-to-the-serial-console) using Mu or a terminal program.
2. Type the following into the REPL:
```terminal
>>> import storage
>>> storage.erase_filesystem()
```
CIRCUITPY will be erased and reformatted, and your board will restart. That's it!
## Erase CIRCUITPY Without Access to the REPL
If you can't access the REPL, or you're running a version of CircuitPython previous to 2.3.0 and you don't want to upgrade, there are options available for some specific boards.
**The options listed below are considered to be the "old way" of erasing your board. The method shown above using the REPL is highly recommended as the best method for erasing your board.**
Warning:
## For the specific boards listed below:
If the board you are trying to erase is listed below, follow the steps to use the file to erase your board.
1. Download the correct erase file:
[Circuit Playground Express](https://cdn-learn.adafruit.com/assets/assets/000/048/745/original/flash_erase_express.ino.circuitplay.uf2?1512152080)
[Feather M0 Express](https://cdn-learn.adafruit.com/assets/assets/000/048/746/original/flash_erase_express.ino.feather_m0_express.uf2?1512152098)
[Feather M4 Express](https://cdn-learn.adafruit.com/assets/assets/000/076/217/original/flash_erase.ino.feather_m4.uf2)
[Metro M0 Express](https://cdn-learn.adafruit.com/assets/assets/000/048/747/original/flash_erase_express.ino.metro_m0.uf2?1512152103)
[Metro M4 Express QSPI Eraser](https://cdn-learn.adafruit.com/assets/assets/000/073/820/original/Metro_M4_QSPI_Eraser.UF2?1553805937)
[Trellis M4 Express (QSPI)](https://cdn-learn.adafruit.com/assets/assets/000/067/535/original/Trellis_M4_QSPI_Eraser.UF2?1544719380)
[Grand Central M4 Express (QSPI)](https://cdn-learn.adafruit.com/assets/assets/000/069/314/original/GC_M4_QSPI_Erase.UF2?1547404471)
[PyPortal M4 Express (QSPI)](https://cdn-learn.adafruit.com/assets/assets/000/072/252/original/PYPORTAL_QSPI_Eraser.UF2?1551738305)
[Circuit Playground Bluefruit (QSPI)](https://cdn-learn.adafruit.com/assets/assets/000/082/950/original/CP_Bluefruit_QSPI_Erase.UF2?1572026649)
[Monster M4SK (QSPI)](https://cdn-learn.adafruit.com/assets/assets/000/083/330/original/M4SK_QSPI_Eraser.UF2?1572551433)
[PyBadge/PyGamer QSPI Eraser.UF2](https://cdn-learn.adafruit.com/assets/assets/000/083/331/original/PyBadge_QSPI_Eraser.UF2?1572551613)
[CLUE_Flash_Erase.UF2](https://cdn-learn.adafruit.com/assets/assets/000/088/454/original/CLUE_Flash_Erase.UF2?1581873830)
[Matrix_Portal_M4_(QSPI).UF2](https://cdn-learn.adafruit.com/assets/assets/000/098/741/original/Matrix_Portal_M4_%28QSPI%29.UF2?1611076081)
[RP2040 boards (flash_nuke.uf2)](https://cdn-learn.adafruit.com/assets/assets/000/101/659/original/flash_nuke.uf2)
2. Double-click the reset button on the board to bring up the **_boardname_BOOT** drive.
3. Drag the erase **.uf2** file to the **_boardname_BOOT** drive.
4. The status LED will turn yellow or blue, indicating the erase has started.
5. After approximately 15 seconds, the status LED will light up green. On the NeoTrellis M4 this is the first NeoPixel on the grid
6. Double-click the reset button on the board to bring up the **_boardname_BOOT** drive.
7. [Drag the appropriate latest release of CircuitPython](https://circuitpython.org/downloads) **.uf2** file to the **_boardname_BOOT** drive.
It should reboot automatically and you should see **CIRCUITPY** in your file explorer again.
If the LED flashes red during step 5, it means the erase has failed. Repeat the steps starting with 2.
[If you haven't already downloaded the latest release of CircuitPython for your board, check out the installation page](../../../../welcome-to-circuitpython/installing-circuitpython). You'll also need to load your code and reinstall your libraries!
## For SAMD21 non-Express boards that have a UF2 bootloader:
Any SAMD21-based microcontroller that does not have external flash available is considered a SAMD21 non-Express board. Non-Express boards that have a UF2 bootloader include Trinket M0, GEMMA M0, QT Py M0, and the SAMD21-based Trinkey boards.
If you are trying to erase a SAMD21 non-Express board, follow these steps to erase your board.
1. Download the erase file:
[SAMD21 non-Express Boards](https://cdn-learn.adafruit.com/assets/assets/000/048/748/original/erase_m0.uf2)
2. Double-click the reset button on the board to bring up the **_boardname_BOOT** drive.
3. Drag the erase **.uf2** file to the **_boardname_BOOT** drive.
4. The boot LED will start flashing again, and the **_boardname_BOOT** drive will reappear.
5. [Drag the appropriate latest release CircuitPython](https://circuitpython.org/downloads) **.uf2** file to the _boardname_BOOT drive.
It should reboot automatically and you should see **CIRCUITPY** in your file explorer again.
[If you haven't already downloaded the latest release of CircuitPython for your board, check out the installation page](../../../../welcome-to-circuitpython/installing-circuitpython) YYou'll also need to load your code and reinstall your libraries!
## For SAMD21 non-Express boards that do not have a UF2 bootloader:
Any SAMD21-based microcontroller that does not have external flash available is considered a SAMD21 non-Express board. Non-Express boards that do **not** have a UF2 bootloader include the Feather M0 Basic Proto, Feather Adalogger, or the Arduino Zero.
If you are trying to erase a non-Express board that does not have a UF2 bootloader, [follow these directions to reload CircuitPython using `bossac`](../../../../welcome-to-circuitpython/non-uf2-installation), which will erase and re-create **CIRCUITPY**.
# Running Out of File Space on SAMD21 Non-Express Boards
Any SAMD21-based microcontroller that does not have external flash available is considered a SAMD21 non-Express board. This includes boards like the Trinket M0, GEMMA M0, QT Py M0, and the SAMD21-based Trinkey boards.
The file system on the board is very tiny. (Smaller than an ancient floppy disk.) So, its likely you'll run out of space but don't panic! There are a number of ways to free up space.
## Delete something!
The simplest way of freeing up space is to delete files from the drive. Perhaps there are libraries in the **lib** folder that you aren't using anymore or test code that isn't in use. Don't delete the **lib** folder completely, though, just remove what you don't need.
The board ships with the Windows 7 serial driver too! Feel free to delete that if you don't need it or have already installed it. It's ~12KiB or so.
## Use tabs
One unique feature of Python is that the indentation of code matters. Usually the recommendation is to indent code with four spaces for every indent. In general, that is recommended too. **However** , one trick to storing more human-readable code is to use a single tab character for indentation. This approach uses 1/4 of the space for indentation and can be significant when you're counting bytes.
## On macOS?
MacOS loves to generate hidden files. Luckily you can disable some of the extra hidden files that macOS adds by running a few commands to disable search indexing and create zero byte placeholders. Follow the steps below to maximize the amount of space available on macOS.
## Prevent & Remove macOS Hidden Files
First find the volume name for your board. With the board plugged in run this command in a terminal to list all the volumes:
```
ls -l /Volumes
```
Look for a volume with a name like **CIRCUITPY** (the default for CircuitPython). The full path to the volume is the **/Volumes/CIRCUITPY** path.
Now follow the [steps from this question](http://apple.stackexchange.com/questions/6707/how-to-stop-os-x-from-writing-spotlight-and-trash-files-to-memory-cards-and-usb/7135#7135) to run these terminal commands that stop hidden files from being created on the board:
```terminal
mdutil -i off /Volumes/CIRCUITPY
cd /Volumes/CIRCUITPY
rm -rf .{,_.}{fseventsd,Spotlight-V*,Trashes}
mkdir .fseventsd
touch .fseventsd/no_log .metadata_never_index .Trashes
cd -
```
Replace **/Volumes/CIRCUITPY** in the commands above with the full path to your board's volume if it's different. At this point all the hidden files should be cleared from the board and some hidden files will be prevented from being created.
Alternatively, with CircuitPython 4.x and above, the special files and folders mentioned above will be created automatically if you erase and reformat the filesystem. **WARNING: Save your files first!** Do this in the REPL:
`>>> import storage`
`>>> storage.erase_filesystem()`
However there are still some cases where hidden files will be created by MacOS. In particular if you copy a file that was downloaded from the internet it will have special metadata that MacOS stores as a hidden file. Luckily you can run a copy command from the terminal to copy files **without** this hidden metadata file. See the steps below.
## Copy Files on macOS Without Creating Hidden Files
Once you've disabled and removed hidden files with the above commands on macOS you need to be careful to copy files to the board with a special command that prevents future hidden files from being created. Unfortunately you **cannot** use drag and drop copy in Finder because it will still create these hidden extended attribute files in some cases (for files downloaded from the internet, like Adafruit's modules).
To copy a file or folder use the **-X** option for the **cp** command in a terminal. For example to copy a **file\_name.mpy** file to the board use a command like:
```terminal
cp -X file_name.mpy /Volumes/CIRCUITPY
```
(Replace **file\_name.mpy** with the name of the file you want to copy.)
Or to copy a folder and all of the files and folders contained within, use a command like:
```terminal
cp -rX folder_to_copy /Volumes/CIRCUITPY
```
If you are copying to the **lib** folder, or another folder, make sure it exists before copying.
```terminal
# if lib does not exist, you'll create a file named lib !
cp -X file_name.mpy /Volumes/CIRCUITPY/lib
# This is safer, and will complain if a lib folder does not exist.
cp -X file_name.mpy /Volumes/CIRCUITPY/lib/
```
## Other macOS Space-Saving Tips
If you'd like to see the amount of space used on the drive and manually delete hidden files here's how to do so. First, move into the **Volumes/** directory with `cd /Volumes/`, and then list the amount of space used on the **CIRCUITPY** drive with the `df` command.
That's not very much space left! The next step is to show a list of the files currently on the **CIRCUITPY** drive, _including_ the hidden files, using the `ls` command. You cannot use Finder to do this, you must do it via command line!
There are a few of the hidden files that MacOS loves to generate, all of which begin with a **.\_** before the file name. Remove the **.\_** files using the `rm` command. You can remove them all once by running `rm CIRCUITPY/._*`. The `*` acts as a _wildcard_ to apply the command to everything that begins with **.\_** at the same time.
Finally, you can run `df` again to see the current space used.
Nice! You have 12Ki more than before! This space can now be used for libraries and code!
# Device Locked Up or Boot Looping
In rare cases, it may happen that something in your **code.py** or **boot.py** files causes the device to get locked up, or even go into a boot loop. A _boot loop_ occurs when the board reboots repeatedly and never fully loads. These are not caused by your everyday Python exceptions, typically it's the result of a deeper problem within CircuitPython. In this situation, it can be difficult to recover your device if **CIRCUITPY** is not allowing you to modify the **code.py** or **boot.py** files. Safe mode is one recovery option. When the device boots up in safe mode it will not run the **code.py** or **boot.py** scripts, but will still connect the **CIRCUITPY** drive so that you can remove or modify those files as needed.
For more information on safe mode and how to enter safe mode, see the [Safe Mode section on this page](https://learn.adafruit.com/welcome-to-circuitpython/troubleshooting#safe-mode-3105351).
# Adafruit Circuit Playground Bluefruit
## "Uninstalling" CircuitPython
A lot of our boards can be used with multiple programming languages. For example, the Circuit Playground Express can be used with MakeCode, Code.org CS Discoveries, CircuitPython and Arduino.
Maybe you tried CircuitPython and want to go back to MakeCode or Arduino? Not a problem. You can always remove or reinstall CircuitPython _whenever you want!_ Heck, you can change your mind every day!
**There is nothing to uninstall.** CircuitPython is "just another program" that is loaded onto your board. You simply load another program (Arduino or MakeCode) and it will overwrite CircuitPython.
## Backup Your Code
Before replacing CircuitPython, don't forget to make a backup of the code you have on the **CIRCUITPY** drive. That means your **code.py** any other files, the **lib** folder etc. You may lose these files when you remove CircuitPython, so backups are key! Just drag the files to a folder on your laptop or desktop computer like you would with any USB drive.
# Moving Circuit Playground Express to MakeCode
On the Circuit Playground Express ( **this currently does NOT apply to Circuit Playground Bluefruit** ), if you want to go back to using MakeCode, it's really easy. Visit [makecode.adafruit.com](https://makecode.adafruit.com) and find the program you want to upload. Click Download to download the **.uf2** file that is generated by MakeCode.
Now double-click your CircuitPython board until you see the onboard LED(s) turn green and the **...BOOT** directory shows up.
Then find the downloaded MakeCode **.uf2** file and drag it to the **CPLAYBOOT** drive.
Your MakeCode is now running and CircuitPython has been removed. Going forward you only have to **single click** the reset button to get to **CPLAYBOOT**. This is an idiosyncrasy of MakeCode.
# Moving to Arduino
If you want to use Arduino instead, you just use the Arduino IDE to load an Arduino program. Here's an example of uploading a simple "Blink" Arduino program, but you don't have to use this particular program.
Start by plugging in your board, and double-clicking reset until you get the green onboard LED(s).
Within Arduino IDE, select the matching board, say Circuit Playground Express.
Select the correct matching Port:
Create a new simple Blink sketch example:
```
// the setup function runs once when you press reset or power the board
void setup() {
// initialize digital pin 13 as an output.
pinMode(13, OUTPUT);
}
// the loop function runs over and over again forever
void loop() {
digitalWrite(13, HIGH); // turn the LED on (HIGH is the voltage level)
delay(1000); // wait for a second
digitalWrite(13, LOW); // turn the LED off by making the voltage LOW
delay(1000); // wait for a second
}
```
Make sure the LED(s) are still green, then click **Upload** to upload Blink. Once it has uploaded successfully, the serial Port will change so **re-select the new Port**!
Once Blink is uploaded you should no longer need to double-click to enter bootloader mode. Arduino will automatically reset when you upload.
# Adafruit Circuit Playground Bluefruit
## Welcome to the Community!
CircuitPython is a programming language that's super simple to get started with and great for learning. It runs on microcontrollers and works out of the box. You can plug it in and get started with any text editor. The best part? CircuitPython comes with an amazing, supportive community.
Everyone is welcome! CircuitPython is Open Source. This means it's available for anyone to use, edit, copy and improve upon. This also means CircuitPython becomes better because of you being a part of it. Whether this is your first microcontroller board or you're a seasoned software engineer, you have something important to offer the Adafruit CircuitPython community. This page highlights some of the many ways you can be a part of it!
## Adafruit Discord
The Adafruit Discord server is the best place to start. Discord is where the community comes together to volunteer and provide live support of all kinds. From general discussion to detailed problem solving, and everything in between, Discord is a digital maker space with makers from around the world.
There are many different channels so you can choose the one best suited to your needs. Each channel is shown on Discord as "#channelname". There's the #help-with-projects channel for assistance with your current project or help coming up with ideas for your next one. There's the #show-and-tell channel for showing off your newest creation. Don't be afraid to ask a question in any channel! If you're unsure, #general is a great place to start. If another channel is more likely to provide you with a better answer, someone will guide you.
The help with CircuitPython channel is where to go with your CircuitPython questions. #help-with-circuitpython is there for new users and developers alike so feel free to ask a question or post a comment! Everyone of any experience level is welcome to join in on the conversation. Your contributions are important! The #circuitpython-dev channel is available for development discussions as well.
The easiest way to contribute to the community is to assist others on Discord. Supporting others doesn't always mean answering questions. Join in celebrating successes! Celebrate your mistakes! Sometimes just hearing that someone else has gone through a similar struggle can be enough to keep a maker moving forward.
The Adafruit Discord is the 24x7x365 hackerspace that you can bring your granddaughter to.
Visit [https://adafru.it/discord](https://adafru.it/discord)to sign up for Discord. Everyone is looking forward to meeting you!
## CircuitPython.org
Beyond the Adafruit Learn System, which you are viewing right now, the best place to find information about CircuitPython is [circuitpython.org](https://circuitpython.org). Everything you need to get started with your new microcontroller and beyond is available. You can do things like [download CircuitPython for your microcontroller](https://circuitpython.org/downloads) or [download the latest CircuitPython Library bundle](https://circuitpython.org/libraries), or check out [which single board computers support Blinka](https://circuitpython.org/blinka). You can also get to various other CircuitPython related things like Awesome CircuitPython or the Python for Microcontrollers newsletter. This is all incredibly useful, but it isn't necessarily community related. So why is it included here? The [Contributing page](https://circuitpython.org/contributing).
CircuitPython itself is written in C. However, all of the Adafruit CircuitPython libraries are written in _Python_. If you're interested in contributing to CircuitPython on the Python side of things, check out [circuitpython.org/contributing](https://circuitpython.org/contributing). You'll find information pertaining to every Adafruit CircuitPython library GitHub repository, giving you the opportunity to join the community by finding a contributing option that works for you.
Note the date on the page next to **Current Status for** :
If you submit any contributions to the libraries, and do not see them reflected on the Contributing page, it could be that the job that checks for new updates hasn't yet run for today. Simply check back tomorrow!
Now, a look at the different options.
### Pull Requests
The first tab you'll find is a list of **open pull requests**.
GitHub pull requests, or PRs, are opened when folks have added something to an Adafruit CircuitPython library GitHub repo, and are asking for Adafruit to add, or merge, their changes into the main library code. For PRs to be merged, they must first be reviewed. Reviewing is a great way to contribute! Take a look at the list of open pull requests, and pick one that interests you. If you have the hardware, you can test code changes. If you don't, you can still check the code updates for syntax. In the case of documentation updates, you can verify the information, or check it for spelling and grammar. Once you've checked out the update, you can leave a comment letting us know that you took a look. Once you've done that for a while, and you're more comfortable with it, you can consider joining the CircuitPythonLibrarians review team. The more reviewers we have, the more authors we can support. Reviewing is a crucial part of an open source ecosystem, CircuitPython included.
### Open Issues
The second tab you'll find is a list of **open issues**.
GitHub issues are filed for a number of reasons, including when there is a bug in the library or example code, or when someone wants to make a feature request. Issues are a great way to find an opportunity to contribute directly to the libraries by updating code or documentation. If you're interested in contributing code or documentation, take a look at the open issues and find one that interests you.
If you're not sure where to start, you can search the issues by label. Labels are applied to issues to make the goal easier to identify at a first glance, or to indicate the difficulty level of the issue. Click on the dropdown next to "Sort by issue labels" to see the list of available labels, and click on one to choose it.
If you're new to everything, new to contributing to open source, or new to contributing to the CircuitPython project, you can choose "Good first issue". Issues with that label are well defined, with a finite scope, and are intended to be easy for someone new to figure out.
If you're looking for something a little more complicated, consider "Bug" or "Enhancement". The Bug label is applied to issues that pertain to problems or failures found in the library. The Enhancement label is applied to feature requests.
Don't let the process intimidate you. If you're new to Git and GitHub, there is [a guide](https://learn.adafruit.com/contribute-to-circuitpython-with-git-and-github) to walk you through the entire process. As well, there are always folks available on [Discord](https:adafru.it/discord) to answer questions.
### Library Infrastructure Issues
The third tab you'll find is a list of **library infrastructure issues**.
This section is generated by a script that runs checks on the libraries, and then reports back where there may be issues. It is made up of a list of subsections each containing links to the repositories that are experiencing that particular issue. This page is available mostly for internal use, but you may find some opportunities to contribute on this page. If there's an issue listed that sounds like something you could help with, mention it on Discord, or file an issue on GitHub indicating you're working to resolve that issue. Others can reply either way to let you know what the scope of it might be, and help you resolve it if necessary.
### CircuitPython Localization
The fourth tab you'll find is the **CircuitPython Localization** tab.
If you speak another language, you can help translate CircuitPython! The translations apply to informational and error messages that are within the CircuitPython core. It means that folks who do not speak English have the opportunity to have these messages shown to them in their own language when using CircuitPython. This is incredibly important to provide the best experience possible for all users. CircuitPython uses Weblate to translate, which makes it much simpler to contribute translations. You will still need to know some CircuitPython-specific practices and a few basics about coding strings, but as with any CircuitPython contributions, folks are there to help.
Regardless of your skill level, or how you want to contribute to the CircuitPython project, there is an opportunity available. The [Contributing page](https://circuitpython.org/contributing) is an excellent place to start!
## Adafruit GitHub
Whether you're just beginning or are life-long programmer who would like to contribute, there are ways for everyone to be a part of the CircuitPython project. The CircuitPython core is written in C. The libraries are written in Python. GitHub is the best source of ways to contribute to the [CircuitPython core](https://github.com/adafruit/circuitpython), and the [CircuitPython libraries](https://circuitpython.org/contributing/open-issues). If you need an account, visit [https://github.com/](https://github.com/) and sign up.
If you're new to GitHub or programming in general, there are great opportunities for you. For the CircuitPython core, head over to the CircuitPython repository on GitHub, click on "[Issues](https://github.com/adafruit/circuitpython/issues)", and you'll find a list that includes issues labeled "[good first issue](https://github.com/adafruit/circuitpython/issues?q=is%3Aissue+is%3Aopen+label%3A%22good+first+issue%22)". For the libraries, head over to the [Contributing page Issues list](https://circuitpython.org/contributing/open-issues), and use the drop down menu to search for "[good first issue](https://circuitpython.org/contributing/open-issues?label=good-first-issue)". These issues are things that have been identified as something that someone with any level of experience can help with. These issues include options like updating documentation, providing feedback, and fixing simple bugs. If you need help getting started with GitHub, there is an excellent guide on [Contributing to CircuitPython with Git and GitHub](https://learn.adafruit.com/contribute-to-circuitpython-with-git-and-github).
Already experienced and looking for a challenge? Checkout the rest of either issues list and you'll find plenty of ways to contribute. You'll find all sorts of things, from new driver requests, to library bugs, to core module updates. There's plenty of opportunities for everyone at any level!
When working with or using CircuitPython or the CircuitPython libraries, you may find problems. If you find a bug, that's great! The team loves bugs! Posting a detailed issue to GitHub is an invaluable way to contribute to improving CircuitPython. For CircuitPython itself, file an issue [here](https://github.com/adafruit/circuitpython/issues). For the libraries, file an issue on the specific library repository on GitHub. Be sure to include the steps to replicate the issue as well as any other information you think is relevant. The more detail, the better!
Testing new software is easy and incredibly helpful. Simply load the newest version of CircuitPython or a library onto your CircuitPython hardware, and use it. Let us know about any problems you find by posting a new issue to GitHub. Software testing on both stable and unstable releases is a very important part of contributing CircuitPython. The developers can't possibly find all the problems themselves! They need your help to make CircuitPython even better.
On GitHub, you can submit feature requests, provide feedback, report problems and much more. If you have questions, remember that Discord and the Forums are both there for help!
## Adafruit Forums
The [Adafruit Forums](https://forums.adafruit.com) are the perfect place for support. Adafruit has wonderful paid support folks to answer any questions you may have. Whether your hardware is giving you issues or your code doesn't seem to be working, the forums are always there for you to ask. You need an Adafruit account to post to the forums. You can use the same account you use to order from Adafruit.
While Discord may provide you with quicker responses than the forums, the forums are a more reliable source of information. If you want to be certain you're getting an Adafruit-supported answer, the forums are the best place to be.
There are forum categories that cover all kinds of topics, including everything Adafruit. The [Adafruit CircuitPython](https://forums.adafruit.com/viewforum.php?f=60) category under "Supported Products & Projects" is the best place to post your CircuitPython questions.
Be sure to include the steps you took to get to where you are. If it involves wiring, post a picture! If your code is giving you trouble, include your code in your post! These are great ways to make sure that there's enough information to help you with your issue.
You might think you're just getting started, but you definitely know something that someone else doesn't. The great thing about the forums is that you can help others too! Everyone is welcome and encouraged to provide constructive feedback to any of the posted questions. This is an excellent way to contribute to the community and share your knowledge!
## Read the Docs
[Read the Docs](https://circuitpython.readthedocs.io/) is a an excellent resource for a more detailed look at the CircuitPython core and the CircuitPython libraries. This is where you'll find things like API documentation and example code. For an in depth look at viewing and understanding Read the Docs, check out the [CircuitPython Documentation](https://learn.adafruit.com/welcome-to-circuitpython/circuitpython-documentation) page!
# Adafruit Circuit Playground Bluefruit
## CircuitPython Made Easy
# Adafruit Circuit Playground Bluefruit
## CircuitPython Playground
Here are examples of some of the many things you can do with the Circuit Playground Bluefruit with CircuitPython!
Info:
# Adafruit Circuit Playground Bluefruit
## CircuitPython Pins and Modules
CircuitPython is designed to run on microcontrollers and allows you to interface with all kinds of sensors, inputs and other hardware peripherals. There are tons of guides showing how to wire up a circuit, and use CircuitPython to, for example, read data from a sensor, or detect a button press. Most CircuitPython code includes hardware setup which requires various modules, such as `board` or `digitalio`. You import these modules and then use them in your code. How does CircuitPython know to look for hardware in the specific place you connected it, and where do these modules come from?
This page explains both. You'll learn how CircuitPython finds the pins on your microcontroller board, including how to find the available pins for your board and what each pin is named. You'll also learn about the modules built into CircuitPython, including how to find all the modules available for your board.
# CircuitPython Pins
When using hardware peripherals with a CircuitPython compatible microcontroller, you'll almost certainly be utilising pins. This section will cover how to access your board's pins using CircuitPython, how to discover what pins and board-specific objects are available in CircuitPython for your board, how to use the board-specific objects, and how to determine all available pin names for a given pin on your board.
## `import board`
When you're using any kind of hardware peripherals wired up to your microcontroller board, the import list in your code will include `import board`. The `board` module is built into CircuitPython, and is used to provide access to a series of board-specific objects, including pins. Take a look at your microcontroller board. You'll notice that next to the pins are pin labels. You can always access a pin by its pin label. However, there are almost always multiple names for a given pin.
To see all the available board-specific objects and pins for your board, enter the REPL (`>>>`) and run the following commands:
```python
import board
dir(board)
```
Here is the output for the QT Py SAMD21. **You may have a different board, and this list will vary, based on the board.**
The following pins have labels on the physical QT Py SAMD21 board: A0, A1, A2, A3, SDA, SCL, TX, RX, SCK, MISO, and MOSI. You see that there are many more entries available in `board` than the labels on the QT Py.
You can use the pin names on the physical board, regardless of whether they seem to be specific to a certain protocol.
For example, you do not _have_ to use the SDA pin for I2C - you can use it for a button or LED.
On the flip side, there may be multiple names for one pin. For example, on the QT Py SAMD21, pin **A0** is labeled on the physical board silkscreen, but it is available in CircuitPython as both `A0` and `D0`. For more information on finding all the names for a given pin, see the [What Are All the Available Pin Names?](https://learn.adafruit.com/circuitpython-essentials/circuitpython-pins-and-modules#what-are-all-the-available-names-3082670-14) section below.
The results of `dir(board)` for CircuitPython compatible boards will look similar to the results for the QT Py SAMD21 in terms of the pin names, e.g. A0, D0, etc. However, some boards, for example, the Metro ESP32-S2, have different styled pin names. Here is the output for the Metro ESP32-S2.
Note that most of the pins are named in an IO# style, such as **IO1** and **IO2**. Those pins on the physical board are labeled only with a number, so an easy way to know how to access them in CircuitPython, is to run those commands in the REPL and find the pin naming scheme.
Info:
## I2C, SPI, and UART
You'll also see there are often (_ **but not always!** _) three special board-specific objects included: `I2C`, `SPI`, and `UART` - each one is for the default pin-set used for each of the three common protocol busses they are named for. These are called _singletons_.
What's a singleton? When you create an object in CircuitPython, you are _instantiating_ ('creating') it. Instantiating an object means you are creating an instance of the object with the unique values that are provided, or "passed", to it.
For example, When you instantiate an I2C object using the `busio` module, it expects two pins: clock and data, typically SCL and SDA. It often looks like this:
```python
i2c = busio.I2C(board.SCL, board.SDA)
```
Then, you pass the I2C object to a driver for the hardware you're using. For example, if you were using the TSL2591 light sensor and its CircuitPython library, the next line of code would be:
```python
tsl2591 = adafruit_tsl2591.TSL2591(i2c)
```
However, CircuitPython makes this simpler by including the `I2C` singleton in the `board` module. Instead of the two lines of code above, you simply provide the singleton as the I2C object. So if you were using the TSL2591 and its CircuitPython library, the two above lines of code would be replaced with:
```python
tsl2591 = adafruit_tsl2591.TSL2591(board.I2C())
```
Info:
This eliminates the need for the `busio` module, and simplifies the code. Behind the scenes, the `board.I2C()` object is instantiated when you call it, but not before, and on subsequent calls, it returns the same object. Basically, it does not create an object until you need it, and provides the same object every time you need it. You can call `board.I2C()` as many times as you like, and it will always return the same object.
Info:
## What Are All the Available Names?
Many pins on CircuitPython compatible microcontroller boards have multiple names, however, typically, there's only one name labeled on the physical board. So how do you find out what the other available pin names are? Simple, with the following script! Each line printed out to the serial console contains the set of names for a particular pin.
On a microcontroller board running CircuitPython, first, connect to the serial console.
In the example below, click the **Download Project Bundle** button below to download the necessary libraries and the **code.py** file in a zip file. Extract the contents of the zip file, open the directory **CircuitPython\_Essentials/Pin\_Map\_Script/** and then click on the directory that matches the version of CircuitPython you're using and copy the contents of that directory to your **CIRCUITPY** drive.
Your **CIRCUITPY** drive should now look similar to the following image:
https://github.com/adafruit/Adafruit_Learning_System_Guides/blob/main/CircuitPython_Essentials/Pin_Map_Script/code.py
Here is the result when this script is run on QT Py SAMD21:
Each line represents a single pin. Find the line containing the pin name that's labeled on the physical board, and you'll find the other names available for that pin. For example, the first pin on the board is labeled **A0**. The first line in the output is `board.A0 board.D0 (PA02)`. This means that you can access pin **A0** in CircuitPython using both `board.A0` and `board.D0`.
The pins in parentheses are the microcontroller pin names. See the next section for more info on those.
You'll notice there are two "pins" that aren't labeled on the board but appear in the list: `board.NEOPIXEL` and `board.NEOPIXEL_POWER`. Many boards have several of these special pins that give you access to built-in board hardware, such as an LED or an on-board sensor. The QT Py SAMD21 only has one on-board extra piece of hardware, a NeoPixel LED, so there's only the one available in the list. But you can also control whether or not power is applied to the NeoPixel, so there's a separate pin for that.
That's all there is to figuring out the available names for a pin on a compatible microcontroller board in CircuitPython!
## Microcontroller Pin Names
The pin names available to you in the CircuitPython `board` module are not the same as the names of the pins on the microcontroller itself. The board pin names are aliases to the microcontroller pin names. If you look at the datasheet for your microcontroller, you'll likely find a pinout with a series of pin names, such as "PA18" or "GPIO5". If you want to get to the actual microcontroller pin name in CircuitPython, you'll need the `microcontroller.pin` module. As with `board`, you can run `dir(microcontroller.pin)` in the REPL to receive a list of the microcontroller pin names.
# CircuitPython Built-In Modules
There is a set of modules used in most CircuitPython programs. One or more of these modules is always used in projects involving hardware. Often hardware requires installing a separate library from the Adafruit CircuitPython Bundle. But, if you try to find `board` or `digitalio` in the same bundle, you'll come up lacking. So, where do these modules come from? They're built into CircuitPython! You can find an comprehensive list of built-in CircuitPython modules and the technical details of their functionality from CircuitPython [here](https://circuitpython.readthedocs.io/en/latest/shared-bindings/index.html#modules) and the Python-like modules included [here](https://circuitpython.readthedocs.io/en/latest/docs/library/index.html). However, **not every module is available for every board** due to size constraints or hardware limitations. How do you find out what modules are available for your board?
There are two options for this. You can check the [support matrix](https://circuitpython.readthedocs.io/en/latest/shared-bindings/support_matrix.html#), and search for your board by name. Or, you can use the REPL.
Plug in your board, connect to the serial console and enter the REPL. Type the following command.
```python
help("modules")
```
![](https://cdn-learn.adafruit.com/assets/assets/000/099/208/medium800/circuitpython_Essentials_help_modules_QT_Py.png?1612372532 help("modules") results for QT Py)
That's it! You now know two ways to find all of the modules built into CircuitPython for your compatible microcontroller board.
# Adafruit Circuit Playground Bluefruit
## CircuitPython Built-Ins
CircuitPython comes 'with the kitchen sink' - _a lot_ of the things you know and love about classic Python 3 (sometimes called CPython) already work. There are a few things that don't but we'll try to keep this list updated as we add more capabilities!
Info:
# Thing That Are Built In and Work
## Flow Control
All the usual `if`, `elif`, `else`, `for`, `while` work just as expected.
## Math
`import math` will give you a range of handy mathematical functions.
`>>> dir(math)`
`[' __name__', 'e', 'pi',
'sqrt', 'pow', 'exp', 'log', 'cos', 'sin', 'tan', 'acos', 'asin',
'atan', 'atan2', 'ceil', 'copysign', 'fabs', 'floor', 'fmod', 'frexp',
'ldexp', 'modf', 'isfinite', 'isinf', 'isnan', 'trunc', 'radians',
'degrees']`
CircuitPython supports 30-bit wide floating point values so you can use `int` and `float` whenever you expect.
## Tuples, Lists, Arrays, and Dictionaries
You can organize data in `()`, `[]`, and `{}` including strings, objects, floats, etc.
## Classes, Objects and Functions
We use objects and functions extensively in our libraries so check out one of our many examples like this [MCP9808 library](https://github.com/adafruit/Adafruit_CircuitPython_MCP9808/blob/master/adafruit_mcp9808.py) for class examples.
## Lambdas
Yep! You can create function-functions with `lambda` just the way you like em:
`>>> g = lambda x: x**2`
`>>> g(8)`
`64`
## Random Numbers
To obtain random numbers:
`import random`
`random.random()` will give a floating point number from `0` to `1.0`.
`random.randint(min, max)` will give you an integer number between `min` and `max`.
# Adafruit Circuit Playground Bluefruit
## CircuitPython Digital In & Out
Info:
The first part of interfacing with hardware is being able to manage digital inputs and outputs. With Circuitpython it's super easy!
This quick-start example shows how you can use one of the Circuit Playground Express buttons as an _input_ to control another digital _output_ - the built in LED
In the example below, click the **Download Project Bundle** button below to download the necessary files in a zip file. Extract the contents of the zip file, open the directory **Introducing\_CircuitPlaygroundExpress/CircuitPlaygroundExpress\_DigitalIO/** and then click on the directory that matches the version of CircuitPython you're using and copy **code.py** to your **CIRCUITPY** drive.
Your **CIRCUITPY** drive should now look similar to the following image:
https://github.com/adafruit/Adafruit_Learning_System_Guides/blob/main/Introducing_CircuitPlaygroundExpress/CircuitPlaygroundExpress_DigitalIO/code.py
Info:
Note that we made the code a little less 'pythonic' than necessary, the if/then could be replaced with a simple `led.value = not button.value` but I wanted to make it super clear how to test the inputs. When the interpreter gets to evaluating `button.value` that is when it will read the digital input.
Press Button A (the one on the left), and the onboard red LED will turn on!
Note that on the M0/SAMD based CircuitPython boards, at least, you can also have internal pullups with `Pull.UP` when using external buttons, but the built in buttons require `Pull.DOWN`.
Maybe you're setting up your own external button with pullup or pulldown resistor. If you want to turn off the internal pullup/pulldown simply include `button.switch_to_input()`.
## Going Beyond the Lesson!
It's time to flex your new learnings and try something different!!
### **Experiment 1**
See if you can adjust your code so that you use Button B instead of Button A.
It only takes a small change to switch buttons. If you get stuck, click on the blurry text below to reveal a hint and then the answer:
You need to change one single, solitary letter!
`button = digitalio.DigitalInOut(board.BUTTON_B)`
### **Experiment 2**
Perhaps you want to be sure there are no accidental illuminations of the red LED! Make it so that BOTH buttons must be pressed in order to light the red LED.
Hints:
You'll need to declare a variable for the second button, just as you did with the first. You'll also need to set it up as an input, with pull down resistance.
It's a good idea to rename the original **button** variable to **buttonA, ** and the new set to **buttonB.**
To check both buttons in the 'if' statement, you'll use an 'and' to string together both value checks.
` if buttonA.value and buttonB.value:`
Experiment 3
Try testing the slide switch instead of the buttons. For the slide switch you need to use **Pull.UP** instead of **Pull.DOWN**.
Hints:
`switch = digitalio.DigitalInOut(board.SLIDE_SWITCH)switch.direction = digitalio.Direction.INPUTswitch.pull = digitalio.Pull.UP`
`if switch.value: # switch is slid to the left`
# Adafruit Circuit Playground Bluefruit
## CircuitPython Analog In
Info:
This quick-start example shows how you can read the analog voltage of a potentiometer connected to the Circuit Playground Express.
First, connect your potentiometer to the Circuit Playground Express using three alligator clip leads, as shown. The connections are:
- Left pot connection to **3.3V**
- Center pot (wiper) to **A1**
- Right pot connection to **GND**
Info:
In the example below, click the **Download Project Bundle** button below to download the necessary files in a zip file. Extract the contents of the zip file, open the directory **Introducing\_CircuitPlaygroundExpress/CircuitPlaygroundExpress\_AnalogIn/** and then click on the directory that matches the version of CircuitPython you're using and copy **code.py** to your **CIRCUITPY** drive.
Your **CIRCUITPY** drive should now look similar to the following image:
https://github.com/adafruit/Adafruit_Learning_System_Guides/blob/main/Introducing_CircuitPlaygroundExpress/CircuitPlaygroundExpress_AnalogIn/code.py
## Creating an Analog Input
`analogin = analogio.AnalogIn(board.A1)` creates an object named `analogin` which is connected to the A1 pad on the Circuit Playground Express.
Info:
## GetVoltage Helper
`getVoltage(pin)` is our little helper program. By default, analog readings will range from 0 (minimum) to 65535 (maximum). This helper will convert the 0-65535 reading from `pin.value` and convert it a 0-3.3V voltage reading.
## Main Loop
The main loop is simple, it will just print out the voltage as a floating point value (the `%f` indicates to print as **f** loating point) by calling `getVoltage` on each of our analog object, in this case the potentiometer.
If you connect to the serial console, you'll see the voltage printed out. Try turning the knob of the potentiometer to see the voltage change!
# Adafruit Circuit Playground Bluefruit
## CircuitPython Servo
In order to use servos, we take advantage of `pwmio`. Now, in theory, you could just use the raw `pwmio` calls to set the frequency to 50 Hz and then set the pulse widths. But we would rather make it a little more elegant and easy!
So, instead we will use `adafruit_motor` which manages servos for you quite nicely! `adafruit_motor` is a library so be sure to [grab it from the library bundle if you have not yet](https://circuitpython.org/libraries)! If you need help installing the library, check out the [CircuitPython Libraries page](../../../../welcome-to-circuitpython/circuitpython-libraries).
Servos come in two types:
- A **standard hobby servo** - the horn moves 180 degrees (90 degrees in each direction from zero degrees).
- A **continuous servo** - the horn moves in full rotation like a DC motor. Instead of an angle specified, you set a throttle value with 1.0 being full forward, 0.5 being half forward, 0 being stopped, and -1 being full reverse, with other values between.
## Servo Wiring
Warning:
The connections for a servo are the same for standard servos and continuous rotation servos.
Connect the servo's **brown** or **black** ground wire to ground on the CircuitPython board.
Connect the servo's **red** power wire to 5V power. USB power can in some cases good for a servo or two. But some USB ports supply limited current, and operating a servo from the USB 5V line may cause a power brownout and board crash.
For more servos, you'll need an external battery pack or external power supply. Do not use 3.3V for powering a servo!
Connect the servo's **yellow** or **white** signal wire to the control/data pin, in this case **A1 or** **A2** but you can use any PWM-capable pin.
For example, to wire a servo to **Trinket** , connect the ground wire to **GND** , the power wire to **USB** , and the signal wire to **0**.
Remember, **A2 on Trinket is labeled "0"**.
For **Gemma** , use jumper wire alligator clips to connect the ground wire to **GND** , the power wire to **VOUT** , and the signal wire to **A2**.
For **Circuit Playground Express and Circuit Playground Bluefruit** , use jumper wire alligator clips to connect the ground wire to **GND** , the power wire to **VOUT** , and the signal wire to **A2**.
For **QT Py M0** , connect the ground wire to **GND** , the power wire to **5V** , and the signal wire to **A2**.
For boards like **Feather M0 Express** , **ItsyBitsy M0 Express** and **Metro M0 Express** , connect the ground wire to any **GND** , the power wire to **USB or 5V** , and the signal wire to **A2**.
For the **Metro M4 Express** , **ItsyBitsy M4 Express** and the **Feather M4 Express** , connect the ground wire to any **G or** **GND** , the power wire to **USB or** **5V** , and the signal wire to **A2**.
## Standard Servo Code
Here's an example that will sweep a servo connected to pin **A2** from 0 degrees to 180 degrees (-90 to 90 degrees) and back.
To use with CircuitPython, you need to first install a few libraries, into the lib folder on your **CIRCUITPY** drive. Then you need to update **code.py** with the example script.
Thankfully, we can do this in one go. In the example below, click the **Download Project Bundle** button below to download the necessary libraries and the **code.py** file in a zip file. Extract the contents of the zip file, open the directory **CircuitPython\_Essentials/CircuitPython\_Servo/** and then click on the directory that matches the version of CircuitPython you're using and copy the contents of that directory to your **CIRCUITPY** drive.
Your **CIRCUITPY** drive should now look similar to the following image:
https://github.com/adafruit/Adafruit_Learning_System_Guides/blob/main/CircuitPython_Essentials/CircuitPython_Servo/code.py
## Continuous Servo Code
There are two differences with Continuous Servos vs. Standard Servos:
1. The `servo` object is created like `my_servo = servo.ContinuousServo(pwm)` instead of `my_servo = servo.Servo(pwm)`
2. Instead of using `myservo.angle`, you use `my_servo.throttle` using a throttle value from 1.0 (full on) to 0.0 (stopped) to -1.0 (full reverse). Any number between would be a partial speed forward (positive) or reverse (negative). This is very similar to standard DC motor control with the **adafruit\_motor** library.
This example runs full forward for 2 seconds, stops for 2 seconds, runs full reverse for 2 seconds, then stops for 4 seconds.
To use with CircuitPython, you need to first install a few libraries, into the lib folder on your **CIRCUITPY** drive. Then you need to update **code.py** with the example script.
Thankfully, we can do this in one go. In the example below, click the **Download Project Bundle** button below to download the necessary libraries and the **code.py** file in a zip file. Extract the contents of the zip file, open the directory **CircuitPython\_Essentials/CircuitPython\_Continuous\_Servo/** and then click on the directory that matches the version of CircuitPython you're using and copy the contents of that directory to your **CIRCUITPY** drive.
Your **CIRCUITPY** drive should now look similar to the following image:
https://github.com/adafruit/Adafruit_Learning_System_Guides/blob/main/CircuitPython_Essentials/CircuitPython_Continuous_Servo/code.py
Pretty simple!
Note that we assume that 0 degrees is 0.5ms and 180 degrees is a pulse width of 2.5ms. That's a bit wider than the _official_ 1-2ms pulse widths. If you have a servo that has a different range you can initialize the `servo` object with a different `min_pulse` and `max_pulse`. For example:
`my_servo = servo.Servo(pwm, min_pulse = 500, max_pulse = 2500)`
For more detailed information on using servos with CircuitPython, check out the [CircuitPython section of the servo guide](../../../../using-servos-with-circuitpython/circuitpython)!
# Adafruit Circuit Playground Bluefruit
## CircuitPython Audio Out
Info:
The Circuit Playground Express has some nice built in audio output capabilities.
There are **two** ways to get audio output, one is via the small built in speaker. The other is by using alligator clips to connect a headphone or powered speaker to the **A0/AUDIO** pin.
The speaker is over here, its small but can make some loud sounds! You can **ENABLE** or disable the speaker. If you disable the speaker, audio will only come out the **A0/AUDIO** pin. If you enable the speaker, audio will come out from both!
If you want to connect a speaker or headphones, use two alligator clips and connect **GND** to the sleeve of the headphone, and **A0/AUDIO** to the tip.
Warning:
# Basic Tones
We can start by making simple tones. We will play sine waves. We first generate a single period of a sine wave in python, with the `math.sin` function, and stick it into `sine_wave`.
Then we enable the speaker by setting the `SPEAKER_ENABLE` pin to be an output and `True`.
We can create the audio object with this line that sets the output pin and the sine wave sample object and give it the sample array
`audio = AudioOut(board.SPEAKER)sine_wave_sample = RawSample(sine_wave)`
Finally you can run `audio.play()` - if you only want to play the sample once, call as is. If you want it to _loop_ the sample, which we definitely do so its one long tone, pass in `loop=True`
You can then do whatever you like, the tone will play in the background until you call `audio.stop()`
In the example below, click the **Download Project Bundle** button below to download the necessary files in a zip file. Extract the contents of the zip file, open the directory **Introducing\_CircuitPlaygroundExpress/CircuitPlaygroundExpress\_AudioSine/** and then click on the directory that matches the version of CircuitPython you're using and copy **code.py** to your **CIRCUITPY** drive.
Your **CIRCUITPY** drive should now look similar to the following image:
https://github.com/adafruit/Adafruit_Learning_System_Guides/blob/main/Introducing_CircuitPlaygroundExpress/CircuitPlaygroundExpress_AudioSine/code.py
# Playing Audio Files
Tones are lovely but lets play some music! You can drag-and-drop audio files onto the **CIRCUITPY** drive and then play them with a Python command
## Installing Project Code
To use with CircuitPython, you need to first install a few libraries, into the lib folder on your **CIRCUITPY** drive. Then you need to update **code.py** with the example script.
Thankfully, we can do this in one go. In the example below, click the **Download Project Bundle** button below to download the necessary libraries and the **code.py** file in a zip file. Extract the contents of the zip file, open the directory **Introducing\_CircuitPlaygroundExpress/CircuitPlaygroundExpress\_AudioFiles/** and then click on the directory that matches the version of CircuitPython you're using and copy the contents of that directory to your **CIRCUITPY** drive.
Your **CIRCUITPY** drive should now look similar to the following image:
https://github.com/adafruit/Adafruit_Learning_System_Guides/blob/main/Introducing_CircuitPlaygroundExpress/CircuitPlaygroundExpress_AudioFiles/code.py
This example creates two input buttons using the onboard buttons, then has a helper function that will:
1. open a file on the disk drive with `wave_file = open(filename, "rb")`
2. create the wave file object with `with WaveFile(wave_file) as wave:`
3. create the audio playback object with `with AudioOut(board.SPEAKER) as audio:`
4. and finally play it until its done:
`audio.play(wave)while audio.playing: pass`
Upload the code then try pressing the two buttons one at a time to create your own laugh track!
If you want to use your own sound files, you can! Record, sample, remix, or simply download files from a sound file site, such as freesample.org. Then, to make sure you have the files converted to the proper specifications, [check out this guide here](https://learn.adafruit.com/microcontroller-compatible-audio-file-conversion) that'll show you how! Spoiler alert: you'll need to make a small, 22Khz (or lower), 16 bit PCM, mono .wav file!
# Adafruit Circuit Playground Bluefruit
## CircuitPython Cap Touch
Info:
This quick-start example shows how you can read the capacitive touch sensors built into on seven of the Circuit Playground Express pads (pad **A0/Audio** is not a capacitive touch pad).
In the example below, click the **Download Project Bundle** button below to download the necessary files in a zip file. Extract the contents of the zip file, open the directory **Introducing\_CircuitPlaygroundExpress/CircuitPlaygroundExpress\_CapTouch/** and then click on the directory that matches the version of CircuitPython you're using and copy **code.py** to your **CIRCUITPY** drive.
Your **CIRCUITPY** drive should now look similar to the following image:
https://github.com/adafruit/Adafruit_Learning_System_Guides/blob/main/Introducing_CircuitPlaygroundExpress/CircuitPlaygroundExpress_CapTouch/code.py
You can open up the serial console, then touch each touch pad to see the touches detected and printed out.
## Creating an capacitive touch input
Pads **A1 - A6 and TX** can be used as capacitive TouchIn devices:
`touch_A1 = touchio.TouchIn(board.A1)touch_A2 = touchio.TouchIn(board.A2)touch_A3 = touchio.TouchIn(board.A3)touch_A4 = touchio.TouchIn(board.A4)touch_A5 = touchio.TouchIn(board.A5)touch_A6 = touchio.TouchIn(board.A6)touch_TX = touchio.TouchIn(board.TX)`
This code creates seven objects, one connected to each of the cap touch pads.
## Main Loop
The main loop checks each sensor one after the other, to determine if it has been touched. If `touch_A1.value` returns True, that means that that pad, `A1`, detected a touch. For each pad, if it has been touched, a message will print.
A small sleep delay is added at the end so the loop doesn't run _too_ fast. You may want to change the delay from 0.1 seconds to 0 seconds to slow it down or increase it to speed it up.
Note that no extra hardware is required, you can touch the pads directly, but you may want to attach alligator clips or foil tape to metallic or conductive objects. Try silverware, fruit or other food, liquid, aluminum foil, and items around your desk!
You may need to restart your code/board after changing the attached item because the capacitive touch code 'calibrates' based on what it sees when it first starts up. So if you get too many touch-signals or not enough, hit that reset button!
### Copper Foil Tape with Conductive Adhesive - 6mm x 15 meter roll
[Copper Foil Tape with Conductive Adhesive - 6mm x 15 meter roll](https://www.adafruit.com/product/1128)
Copper tape can be an interesting addition to your toolbox. The tape itself is made of thin pure copper so its extremely flexible and can take on nearly any shape. You can easily solder to it, and the tape itself can carry current just like a wire. On the back is an electrically conductive...
In Stock
[Buy Now](https://www.adafruit.com/product/1128)
[Related Guides to the Product](https://learn.adafruit.com/products/1128/guides)
### Copper Foil Tape with Conductive Adhesive - 25mm x 15 meter roll
[Copper Foil Tape with Conductive Adhesive - 25mm x 15 meter roll](https://www.adafruit.com/product/1127)
Copper tape can be an interesting addition to your toolbox. The tape itself is made of thin pure copper so its extremely flexible and can take on nearly any shape. You can easily solder to it, and the tape itself can carry current just like a wire. On the back is an electrically conductive...
In Stock
[Buy Now](https://www.adafruit.com/product/1127)
[Related Guides to the Product](https://learn.adafruit.com/products/1127/guides)
## Capacitive Touch and the Audio Pin on Circuit Playground Bluefruit
On the Circuit Playground Bluefruit, if you touch any of the touch pads at the same time as touching the Audio pin, you may hear a clicking or buzzing coming from the speaker. This is due to how the capacitive touch on the Bluefruit works. If you run into this and wish to avoid it, you can turn the speaker off using code by including the following in your **code.py** :
```
import digitalio
speaker = digitalio.DigitalInOut(board.SPEAKER_ENABLE)
speaker.switch_to_output(value=False)
```
# Adafruit Circuit Playground Bluefruit
## CircuitPython NeoPixel
Info:
NeoPixels are a revolutionary and ultra-popular way to add lights and color to your project. These stranded RGB lights have the controller inside the LED, so you just push the RGB data and the LEDs do all the work for you! They're a perfect match for CircuitPython.
You can drive 300 pixels with brightness control (e.g. setting `brightness=0.2` to set it to 20% brightness) and 1000 pixels without (e.g. not setting `brightness` at all or setting `brightness=1.0` in object creation). That's because to adjust the brightness we have to dynamically re-create the datastream each write.
Here's an example with a lot of different visual effects you can check out.
In the example below, click the **Download Project Bundle** button below to download the necessary libraries and the **code.py** file in a zip file. Extract the contents of the zip file, open the directory **Introducing\_CircuitPlaygroundExpress/CircuitPlaygroundExpress\_NeoPixel/** and then click on the directory that matches the version of CircuitPython you're using and copy the contents of that directory to your **CIRCUITPY** drive.
Your **CIRCUITPY** drive should now look similar to the following image:
https://github.com/adafruit/Adafruit_Learning_System_Guides/blob/main/Introducing_CircuitPlaygroundExpress/CircuitPlaygroundExpress_NeoPixel/code.py
The NeoPixel object's argument list requires the pin you'll use (any pin can be used) and the number of pixels. There are two optional arguments, `brightness` (range from 0 off to 1.0 full brightness) and `auto_write`. `auto_write` defaults to `True` when not set. When `auto_write` is set to `True`, every change is immediately written to the strip of pixels, which is easier to use but _way_ slower. if you set `auto_write=False` then you will have to call `pixels.show()` when you want to actually write color data out.
You can easily set colors by indexing into the location `pixels[n] = (red, green, blue)`. For example, `pixels[0] = (100, 0, 0)` will set the first pixel to a medium-brightness red, and `pixels[2] = (0, 255, 0)` will set the third pixel to bright green. Then, if you have `auto_write=False` don't forget to call `pixels.show()`!
Info:
For powering the pixels from the board, the 3.3V regulator output can handle about 500mA peak which is about 50 pixels with 'average' use. If you want really bright lights and a lot of pixels, we recommend powering direct from the power source. On the Circuit Playground Express this is the **Vout** pad - that pad has direct power from USB or BAT (battery), depending on which is higher voltage.
Verify the wiring on your strip or device - plugging into the 'DOUT' side is a common mistake! Wire up NeoPixels only while the Circuit Playground Express is not on, to avoid possible damage!
If the power to the NeoPixels is \> 5.5V you may have some difficulty driving some strips, in which case you may need to lower the voltage to 4.5-5V or use a level shifter
Info:
# Adafruit Circuit Playground Bluefruit
## CircuitPython DotStar
DotStars use two wires, unlike NeoPixel's one wire. They're very similar but you can write to DotStars much faster with hardware SPI _and_ they have a faster PWM cycle so they are better for light painting.
Any pins can be used **but** if the two pins can form a hardware SPI port, the library will automatically switch over to hardware SPI. If you use hardware SPI then you'll get 4 MHz clock rate (that would mean updating a 64 pixel strand in about 500uS - that's 0.0005 seconds). If you use non-hardware SPI pins you'll drop down to about 3KHz, 1000 times as slow!
You can drive 300 DotStar LEDs with brightness control (set `brightness=1.0` in object creation) and 1000 LEDs without. That's because to adjust the brightness we have to dynamically recreate the data-stream each write.
You'll need the **adafruit\_dotstar.mpy** library if you don't already have it in your /lib folder! You can get it from the [CircuitPython Library Bundle](https://circuitpython.org/libraries). If you need help installing the library, check out the [CircuitPython Libraries page](../../../../welcome-to-circuitpython/circuitpython-libraries).
## Wire It Up
You'll need to solder up your DotStars first. Verify your connection is on the **DATA INPUT** or **DI** and **CLOCK INPUT** or **CI** side. Plugging into the DATA OUT/DO or CLOCK OUT/CO side is a common mistake! The connections are labeled and some formats have arrows to indicate the direction the data must flow. Always verify your wiring with a visual inspection, as the order of the connections can differ from strip to strip!
For powering the pixels from the board, the 3.3V regulator output can handle about 500mA peak which is about 50 pixels with 'average' use. If you want really bright lights and a lot of pixels, we recommend powering direct from an external power source.
- On Gemma M0 and Circuit Playground Express this is the **Vout** pad - that pad has direct power from USB or the battery, depending on which is higher voltage.
- On Trinket M0, Feather M0 Express, Feather M4 Express, ItsyBitsy M0 Express and ItsyBitsy M4 Express the **USB** or **BAT** pins will give you direct power from the USB port or battery.
- On Metro M0 Express and Metro M4 Express, use the **5V** pin regardless of whether it's powered via USB or the DC jack.
- On QT Py M0, use the **5V** pin.
If the power to the DotStars is greater than 5.5V you may have some difficulty driving some strips, in which case you may need to lower the voltage to 4.5-5V or use a level shifter.
Warning:
Info:
## The Code
This example includes multiple visual effects.
To use with CircuitPython, you need to first install a few libraries, into the lib folder on your **CIRCUITPY** drive. Then you need to update **code.py** with the example script.
Thankfully, we can do this in one go. In the example below, click the **Download Project Bundle** button below to download the necessary libraries and the **code.py** file in a zip file. Extract the contents of the zip file, open the directory **CircuitPython\_Essentials/CircuitPython\_DotStar/** and then click on the directory that matches the version of CircuitPython you're using and copy the contents of that directory to your **CIRCUITPY** drive.
Your **CIRCUITPY** drive should now look similar to the following image:
https://github.com/adafruit/Adafruit_Learning_System_Guides/blob/main/CircuitPython_Essentials/CircuitPython_DotStar/code.py
Info:
## Create the LED
The first thing we'll do is create the LED object. The DotStar object has three required arguments and two optional arguments. You are required to set the pin you're using for data, set the pin you'll be using for clock, and provide the number of pixels you intend to use. You can optionally set `brightness` and `auto_write`.
**DotStars can be driven by any two pins**. We've chosen **A1** for clock and **A2** for data. To set the pins, include the pin names at the beginning of the object creation, in this case `board.A1` and `board.A2`.
To provide the number of pixels, assign the variable `num_pixels` to the number of pixels you'd like to use. In this example, we're using a strip of `72`.
We've chosen to set `brightness=0.1`, or 10%.
By default, `auto_write=True`, meaning any changes you make to your pixels will be sent automatically. Since `True` is the default, if you use that setting, you don't need to include it in your LED object at all. We've chosen to set `auto_write=False`. If you set `auto_write=False`, you must include `pixels.show()` each time you'd like to send data to your pixels. This makes your code more complicated, but it can make your LED animations faster!
## DotStar Helpers
We've included a few helper functions to create the super fun visual effects found in this code.
First is `wheel()` which we just learned with the [Internal RGB LED](../../../../circuitpython-essentials/circuitpython-internal-rgb-led). Then we have `color_fill()` which requires you to provide a `color` and the length of time you'd like it to be displayed. Next, are `slice_alternating()`, `slice_rainbow()`, and `rainbow_cycle()` which require you to provide the amount of time in seconds you'd between each step of the animation.
Last, we've included a list of variables for our colors. This makes it much easier if to reuse the colors anywhere in the code, as well as add more colors for use in multiple places. Assigning and using RGB colors is explained in [this section of the CircuitPython Internal RGB LED page](../../../../circuitpython-essentials/circuitpython-internal-rgb-led#main-loop).
The two slice helpers utilise a nifty feature of the DotStar library that allows us to use math to light up LEDs in repeating patterns. `slice_alternating()` first lights up the even number LEDs and then the odd number LEDs and repeats this back and forth. `slice_rainbow()` lights up every sixth LED with one of the six rainbow colors until the strip is filled. Both use our handy color variables. This slice code only works when the total number of LEDs is divisible by the slice size, in our case 2 and 6. DotStars come in strips of 30, 60, 72, and 144, all of which are divisible by 2 and 6. In the event that you cut them into different sized strips, the code in this example may not work without modification. However, as long as you provide a total number of LEDs that is divisible by the slices, the code will work.
## Main Loop
Our main loop begins by calling `color_fill()` once for each `color` on our list and sets each to hold for `0.5` seconds. You can change this number to change how fast each color is displayed. Next, we call `slice_alternating(0.1)`, which means there's a 0.1 second delay between each change in the animation. Then, we fill the strip white to create a clean backdrop for the rainbow to display. Then, we call `slice_rainbow(0.1)`, for a 0.1 second delay in the animation. Last we call `rainbow_cycle(0)`, which means it's as fast as it can possibly be. Increase or decrease either of these numbers to speed up or slow down the animations!
Note that the longer your strip of LEDs is, the longer it will take for the animations to complete.
Info:
## Is it SPI?
We explained at the beginning of this section that the LEDs respond faster if you're using hardware SPI. On some of the boards, there are HW SPI pins directly available in the form of MOSI and SCK. However, hardware SPI is available on more than just those pins. But, how can you figure out which? Easy! We wrote a handy script.
We chose pins **A1** and **A2** for our example code. To see if these are hardware SPI on the board you're using, copy and paste the code into **code.py** using your favorite editor, and save the file. Then connect to the serial console to see the results.
To check if other pin combinations have hardware SPI, change the pin names on the line reading: `if is_hardware_SPI(board.A1, board.A2):` to the pins you want to use. Then, check the results in the serial console. Super simple!
In the example below, click the **Download Project Bundle** button below to download the necessary libraries and the **code.py** file in a zip file. Extract the contents of the zip file, open the directory **CircuitPython\_Essentials/SPI\_Test\_Script/** and then click on the directory that matches the version of CircuitPython you're using and copy the contents of that directory to your **CIRCUITPY** drive.
Your **CIRCUITPY** drive should now look similar to the following image:
https://github.com/adafruit/Adafruit_Learning_System_Guides/blob/main/CircuitPython_Essentials/SPI_Test_Script/code.py
## Read the Docs
For a more in depth look at what `dotstar` can do, check out [DotStar on Read the Docs](https://circuitpython.readthedocs.io/projects/dotstar/en/latest/).
# Adafruit Circuit Playground Bluefruit
## CircuitPython UART Serial
In addition to the USB-serial connection you use for the REPL, there is also a _hardware_ UART you can use. This is handy to talk to UART devices like GPSs, some sensors, or other microcontrollers!
This quick-start example shows how you can create a UART device for communicating with hardware serial devices.
To use this example, you'll need something to generate the UART data. We've used a GPS! Note that the GPS will give you UART data without getting a fix on your location. You can use this example right from your desk! You'll have data to read, it simply won't include your actual location.
Warning:
- **LED +** to **QT Py SCK**
- **LED -** to **470Ω resistor**
- **470Ω resistor** to **QT Py GND**
In the example below, click the **Download Project Bundle** button below to download the necessary libraries and the **code.py** file in a zip file. Extract the contents of the zip file, open the directory **CircuitPython\_Essentials/CircuitPython\_UART/** and then click on the directory that matches the version of CircuitPython you're using and copy the contents of that directory to your **CIRCUITPY** drive.
Your **CIRCUITPY** drive should now look similar to the following image:
https://github.com/adafruit/Adafruit_Learning_System_Guides/blob/main/CircuitPython_Essentials/CircuitPython_UART/code.py
Info:
For **QT Py M0** , you'll need to comment out `led = DigitalInOut(board.LED)` and uncomment `led = DigitalInOut(board.SCK)`. The UART code remains the same.
## The Code
First we create the UART object. We provide the pins we'd like to use, `board.TX` and `board.RX`, and we set the `baudrate=9600`. While these pins are labeled on most of the boards, be aware that RX and TX are not labeled on Gemma, and are labeled on the bottom of Trinket. See the diagrams below for help with finding the correct pins on your board.
Once the object is created you read data in with `read(numbytes)` where you can specify the max number of bytes. It will return a byte array type object if anything was received already. Note it will always return immediately because there is an internal buffer! So read as much data as you can 'digest'.
If there is no data available, `read()` will return `None`, so check for that before continuing.
The data that is returned is in a byte array, if you want to convert it to a string, you can use this handy line of code which will run `chr()` on each byte:
`datastr = ''.join([chr(b) for b in data]) # convert bytearray to string`
Your results will look something like this:
Info:
## Wire It Up
You'll need a couple of things to connect the GPS to your board.
For Gemma M0 and Circuit Playground Express, you can use use alligator clips to connect to the Flora Ultimate GPS Module.
For Trinket M0, Feather M0 Express, Metro M0 Express and ItsyBitsy M0 Express, you'll need a breadboard and jumper wires to connect to the Ultimate GPS Breakout.
We've included diagrams show you how to connect the GPS to your board. In these diagrams, the wire colors match the same pins on each board.
- The **black** wire connects between the **ground** pins.
- The **red** wire connects between the **power** pins on the GPS and your board.
- The **blue** wire connects from **TX** on the GPS to **RX** on your board.
- The **white** wire connects from **RX** on the GPS to **TX** on your board.
Check out the list below for a diagram of your specific board!
Warning:
**Circuit Playground Express and Circuit Playground Bluefruit**
- Connect **3.3v** on your CPX to **3.3v** on your GPS.
- Connect **GND** on your CPX to **GND** on your GPS.
- Connect **RX/A6** on your CPX to **TX** on your GPS.
- Connect **TX/A7** on your CPX to **RX** on your GPS.
**Trinket M0**
- Connect **USB** on the Trinket to **VIN** on the GPS.
- Connect **Gnd** on the Trinket to **GND** on the GPS.
- Connect **D3** on the Trinket to **TX** on the GPS.
- Connect **D4** on the Trinket to **RX** on the GPS.
**Gemma M0**
- Connect **3vo** on the Gemma to **3.3v** on the GPS.
- Connect **GND** on the Gemma to **GND** on the GPS.
- Connect **A1/D2** on the Gemma to **TX** on the GPS.
- Connect **A2/D0** on the Gemma to **RX** on the GPS.
**QT Py M0**
- Connect **3V** on the QT Py to **VIN** on the GPS.
- Connect **GND** on the QT Py to **GND** on the GPS.
- Connect **RX** on the QT Py to **TX** on the GPS.
- Connect **TX** on the QT Py to **RX** on the GPS.
**Feather M0 Express and Feather M4 Express**
- Connect **USB** on the Feather to **VIN** on the GPS.
- Connect **GND** on the Feather to **GND** on the GPS.
- Connect **RX** on the Feather to **TX** on the GPS.
- Connect **TX** on the Feather to **RX** on the GPS.
**ItsyBitsy M0 Express and ItsyBitsy M4 Express**
- Connect **USB** on the ItsyBitsy to **VIN** on the GPS
- Connect **G** on the ItsyBitsy to **GND** on the GPS.
- Connect **RX/0** on the ItsyBitsy to **TX** on the GPS.
- Connect **TX/1** on the ItsyBitsy to **RX** on the GPS.
**Metro M0 Express and Metro M4 Express**
- Connect **5V** on the Metro to **VIN** on the GPS.
- Connect **GND** on the Metro to **GND** on the GPS.
- Connect **RX/D0** on the Metro to **TX** on the GPS.
- Connect **TX/D1** on the Metro to **RX** on the GPS.
## Where's my UART?
On the SAMD21, we have the flexibility of using a wide range of pins for UART. Compare this to some chips like the ESP8266 with _fixed_ UART pins. The good news is you can use many but not _all_ pins. Given the large number of SAMD boards we have, its impossible to guarantee anything other than the labeled 'TX' and 'RX'. So, if you want some other setup, or multiple UARTs, how will you find those pins? Easy! We've written a handy script.
These are the results from a Trinket M0, your output may vary and it might be _very_ long. [For more details about UARTs and SERCOMs check out our detailed guide here](../../../../using-atsamd21-sercom-to-add-more-spi-i2c-serial-ports)
In the example below, click the **Download Project Bundle** button below to download the necessary libraries and the **code.py** file in a zip file. Extract the contents of the zip file, open the directory **CircuitPython\_Essentials/UART\_Test\_Script/** and then click on the directory that matches the version of CircuitPython you're using and copy the contents of that directory to your **CIRCUITPY** drive.
Your **CIRCUITPY** drive should now look similar to the following image:
https://github.com/adafruit/Adafruit_Learning_System_Guides/blob/main/CircuitPython_Essentials/UART_Test_Script/code.py
## Trinket M0: Create UART before I2C
On the Trinket M0 (only), if you are using both UART and I2C, you must create the UART object first, e.g.:
```python
>>> import board
>>> uart = board.UART() # Uses pins 4 and 3 for TX and RX, baudrate 9600.
>>> i2c = board.I2C() # Uses pins 2 and 0 for SCL and SDA.
# or alternatively,
```
Creating the I2C object first does not work:
```python
>>> import board
>>> i2c = board.I2C() # Uses pins 2 and 0 for SCL and SDA.
>>> uart = board.UART() # Uses pins 4 and 3 for TX and RX, baudrate 9600.
Traceback (most recent call last):
File "", line 1, in
ValueError: Invalid pins
```
# Adafruit Circuit Playground Bluefruit
## CircuitPython I2C
I2C is a 2-wire protocol for communicating with simple sensors and devices, meaning it uses two connections for transmitting and receiving data. There are many I2C devices available and they're really easy to use with CircuitPython. We have libraries available for many I2C devices in the [library bundle](https://circuitpython.org/libraries). (If you don't see the sensor you're looking for, keep checking back, more are being written all the time!)
In this section, we're going to do is learn how to scan the I2C bus for all connected devices. Then we're going to learn how to interact with an I2C device.
We'll be using the [Adafruit TSL2591](https://www.adafruit.com/product/1980), a common, low-cost light sensor. While the exact code we're running is specific to the TSL2591 the overall process is the same for just about any I2C sensor or device.
These examples will use the TSL2591 lux sensor breakout. The first thing you'll want to do is get the sensor connected so your board has I2C to talk to.
## Wire It Up
You'll need a couple of things to connect the TSL2591 to your board. The TSL2591 comes with STEMMA QT / QWIIC connectors on it, which makes it super simple to wire it up. No further soldering required!
For Gemma M0, Circuit Playground Express and Circuit Playground Bluefruit, you can use use the [STEMMA QT to alligator clips cable](https://www.adafruit.com/product/4398) to connect to the TSL2591.
For Trinket M0, Feather M0 and M4 Express, Metro M0 and M4 Express and ItsyBitsy M0 and M4 Express, you'll need a breadboard and [STEMMA QT to male jumper wires cable](https://www.adafruit.com/product/4209) to connect to the TSL2591.
For QT Py M0, you'll need a [STEMMA QT cable](https://www.adafruit.com/product/4210) to connect to the TSL2591.
We've included diagrams show you how to connect the TSL2591 to your board. In these diagrams, the wire colors match the STEMMA QT cables and connect to the same pins on each board.
- The **black** wire connects from **GND** on the TSL2591 to **ground** on your board.
- The **red** wire connects from **VIN** on the TSL2591 to **power** on your board.
- The **yellow** wire connects from **SCL** on the TSL2591 to **SCL** on your board.
- The **blue** wire connects from **SDA** on the TSL2591 to **SDA** on your board.
Check out the list below for a diagram of your specific board!
Warning:
**Circuit Playground Express and Circuit Playground Bluefruit**
- Connect **3.3v** on your CPX to **3.3v** on your TSL2591.
- Connect **GND** on your CPX to **GND** on your TSL2591.
- Connect **SCL/A4** on your CPX to **SCL** on your TSL2591.
- Connect **SDL/A5** on your CPX to **SDA** on your TSL2591.
**Trinket M0**
- Connect **USB** on the Trinket to **VIN** on the TSL2591.
- Connect **Gnd** on the Trinket to **GND** on the TSL2591.
- Connect **D2** on the Trinket to **SCL** on the TSL2591.
- Connect **D0** on the Trinket to **SDA** on the TSL2591.
**Gemma M0**
- Connect **3vo** on the Gemma to **3V** on the TSL2591.
- Connect **GND** on the Gemma to **GND** on the TSL2591.
- Connect **A1/D2** on the Gemma to **SCL** on the TSL2591.
- Connect **A2/D0** on the Gemma to **SDA** on the TSL2591.
**QT Py M0**
If using the STEMMA QT cable:
- Connect the **STEMMA QT cable** from **the connector on the QT Py** to **the connector on the TSL2591.**
Alternatively, if using a breadboard:
- Connect **3V** on the QT Py to **VIN** on the TSL2591.
- Connect **GND** on the QT Py to **GND** on the TSL2591.
- Connect **SCL** on the QT Py to **SCL** on the TSL2591.
- Connect **SDA** on the QT Py to **SDA** on the TSL2591.
**Feather M0 Express and Feather M4 Express**
- Connect **USB** on the Feather to **VIN** on the TSL2591.
- Connect **GND** on the Feather to **GND** on the TSL2591.
- Connect **SCL** on the Feather to **SCL** on the TSL2591.
- Connect **SDA** on the Feather to **SDA** on the TSL2591.
**ItsyBitsy M0 Express and ItsyBitsy M4 Express**
- Connect **USB** on the ItsyBitsy to **VIN** on the TSL2591
- Connect **G** on the ItsyBitsy to **GND** on the TSL2591.
- Connect **SCL** on the ItsyBitsy to **SCL** on the TSL2591.
- Connect **SDA** on the ItsyBitsy to **SDA** on the TSL2591.
**Metro M0 Express and Metro M4 Express**
- Connect **5V** on the Metro to **VIN** on the TSL2591.
- Connect **GND** on the Metro to **GND** on the TSL2591.
- Connect **SCL** on the Metro to **SCL** on the TSL2591.
- Connect **SDA** on the Metro to **SDA** on the TSL2591.
## Find Your Sensor
The first thing you'll want to do after getting the sensor wired up, is make sure it's wired correctly. We're going to do an I2C scan to see if the board is detected, and if it is, print out its I2C address.
In the example below, click the **Download Project Bundle** button below to download the necessary libraries and the **code.py** file in a zip file. Extract the contents of the zip file, open the directory **CircuitPython\_Essentials/CircuitPython\_I2C\_Scan/** and then click on the directory that matches the version of CircuitPython you're using and copy the contents of that directory to your **CIRCUITPY** drive.
Your **CIRCUITPY** drive should now look similar to the following image:
https://github.com/adafruit/Adafruit_Learning_System_Guides/blob/main/CircuitPython_Essentials/CircuitPython_I2C_Scan/code.py
First we create the `i2c` object, using `board.I2C()`. This convenience routine creates and saves a `busio.I2C` object using the default pins `board.SCL` and `board.SDA`. If the object has already been created, then the existing object is returned. No matter how many times you call `board.I2C()`, it will return the same object. This is called a **singleton**.
To be able to scan it, we need to lock the I2C down so the only thing accessing it is the code. So next we include a loop that waits until I2C is locked and then continues on to the scan function.
Last, we have the loop that runs the actual scan, `i2c_scan()`. Because I2C typically refers to addresses in hex form, we've included this bit of code that formats the results into hex format: `[hex(device_address) for device_address in i2c.scan()]`.
Open the serial console to see the results! The code prints out an array of addresses. We've connected the TSL2591 which has a 7-bit I2C address of 0x29. The result for this sensor is `I2C addresses found: ['0x29']`. If no addresses are returned, refer back to the wiring diagrams to make sure you've wired up your sensor correctly.
## I2C Sensor Data
Now we know for certain that our sensor is connected and ready to go. Let's find out how to get the data from our sensor!
## Installing Project Code
To use with CircuitPython, you need to first install a few libraries, into the lib folder on your **CIRCUITPY** drive. Then you need to update **code.py** with the example script.
Thankfully, we can do this in one go. In the example below, click the **Download Project Bundle** button below to download the necessary libraries and the **code.py** file in a zip file. Extract the contents of the zip file, open the directory **CircuitPython\_Essentials/CircuitPython\_I2C\_TSL2591/** and then click on the directory that matches the version of CircuitPython you're using and copy the contents of that directory to your **CIRCUITPY** drive.
Your **CIRCUITPY** drive should now look similar to the following image:
https://github.com/adafruit/Adafruit_Learning_System_Guides/blob/main/CircuitPython_Essentials/CircuitPython_I2C_TSL2591/code.py
This code begins the same way as the scan code. We've included the scan code so you have verification that your sensor is wired up correctly and is detected. It prints the address once. After the scan, we unlock I2C with `i2c_unlock()` so we can use the sensor for data.
We create our sensor object using the sensor library. We call it `tsl2591` and provide it the `i2c` object.
Then we have a simple loop that prints out the lux reading using the sensor object we created. We add a `time.sleep(1.0)`, so it only prints once per second. Connect to the serial console to see the results. Try shining a light on it to see the results change!
## Where's my I2C?
On the SAMD21, SAMD51 and nRF52840, we have the flexibility of using a wide range of pins for I2C. On the nRF52840, any pin can be used for I2C! Some chips, like the ESP8266, require using bitbangio, but can also use any pins for I2C. There's some other chips that may have fixed I2C pin.
The good news is you can use many but not _all_ pins. Given the large number of SAMD boards we have, its impossible to guarantee anything other than the labeled 'SDA' and 'SCL'. So, if you want some other setup, or multiple I2C interfaces, how will you find those pins? Easy! We've written a handy script.
These are the results from an ItsyBitsy M0 Express. Your output may vary and it might be _very_ long. For more details about I2C and SERCOMs,[check out our detailed guide here](../../../../using-atsamd21-sercom-to-add-more-spi-i2c-serial-ports).
In the example below, click the **Download Project Bundle** button below to download the necessary libraries and the **code.py** file in a zip file. Extract the contents of the zip file, open the directory **CircuitPython\_Essentials/I2C\_Test\_Script/** and then click on the directory that matches the version of CircuitPython you're using and copy the contents of that directory to your **CIRCUITPY** drive.
Your **CIRCUITPY** drive should now look similar to the following image:
https://github.com/adafruit/Adafruit_Learning_System_Guides/blob/main/CircuitPython_Essentials/I2C_Test_Script/code.py
## Clock Speed
For the majority of use cases, the default I2C clock setting (typically 100 kHz) should be fine. However, there are some use cases where changing the I2C clock speed is useful. This will typically be taken care of under the hood by the support library for whatever hardware has this requirement. However, if this needs to be done directly in user code it can be done when setting up the I2C bus.
More information here:
[Clock Speed](https://learn.adafruit.com/working-with-i2c-devices/clock-speed)
# Adafruit Circuit Playground Bluefruit
## CircuitPython HID Keyboard
Info:
One of the things we baked into CircuitPython is 'HID' control - Keyboard and Mouse capabilities. This means a Circuit Playground Express can act like a keyboard device and press keys, or a mouse and have it move the mouse around and press buttons. This is really handy because even if you cannot adapt your software to work with hardware, there's almost always a keyboard interface - so if you want to have a capacitive touch interface for a game, say, then keyboard emulation can often get you going really fast!
Then try running this example code which will set the Circuit Playground Express **Button\_A** and **Button\_B** as HID keyboard "keys".
In the example below, click the **Download Project Bundle** button below to download the necessary libraries and the **code.py** file in a zip file. Extract the contents of the zip file, open the directory **Introducing\_CircuitPlaygroundExpress/CircuitPlaygroundExpress\_HIDKeyboard/** and then click on the directory that matches the version of CircuitPython you're using and copy the contents of that directory to your **CIRCUITPY** drive.
Your **CIRCUITPY** drive should now look similar to the following image:
Warning:
https://github.com/adafruit/Adafruit_Learning_System_Guides/blob/main/Introducing_CircuitPlaygroundExpress/CircuitPlaygroundExpress_HIDKeyboard/code.py
Press Button A or Button B to have the keypresses sent.
The Keyboard and Layout object are created, we only have US right now (if you make other layouts please submit a GitHub pull request!)
`# the keyboard object!`
`kbd = Keyboard(usb_hid.devices)`
`# we're americans :)`
`layout = KeyboardLayoutUS(kbd)`
Then you can send key-down's with `kbd.press(keycode, ...)` You can have up to 6 keycode presses at once. Note that these are **keycodes** so if you want to send a capital A, you need both SHIFT and A. Don't forget to call `kbd.release_all()` soon after or you'll have a stuck key which is really annoying!
You can also send full strings, with `layout.write("Hello World!\n")` - it will use the layout to determine the keycodes to press.
Info:
# Adafruit Circuit Playground Bluefruit
## CircuitPython CPU Temp
There is a CPU temperature sensor built into every ATSAMD21, ATSAMD51 and nRF52840 chips. CircuitPython makes it really simple to read the data from this sensor. This works on the Adafruit CircuitPython boards it's built into the microcontroller used for these boards.
The data is read using two simple commands. We're going to enter them in the REPL. Plug in your board, [connect to the serial console](../../../../welcome-to-circuitpython/kattni-connecting-to-the-serial-console), and [enter the REPL](../../../../welcome-to-circuitpython/the-repl). Then, enter the following commands into the REPL:
```
import microcontroller
microcontroller.cpu.temperature
```
That's it! You've printed the temperature in Celsius to the REPL. Note that it's not exactly the ambient temperature and it's not super precise. But it's close!
If you'd like to print it out in Fahrenheit, use this simple formula: Celsius \* (9/5) + 32. It's super easy to do math using CircuitPython. Check it out!
Info:
# Adafruit Circuit Playground Bluefruit
## CircuitPython Storage
CircuitPython-compatible microcontrollers show up as a **CIRCUITPY** drive when plugged into your computer, allowing you to edit code directly on the board. Perhaps you've wondered whether or not you can write data _from CircuitPython_ directly to the board to act as a data logger. The answer is **yes**!
The `storage` module in CircuitPython enables you to write code that allows CircuitPython to write data to the **CIRCUITPY** drive. This process requires you to include a **boot.py** file on your **CIRCUITPY** drive, along side your **code.py** file.
The **boot.py** file is special - the code within it is executed when CircuitPython starts up, either from a hard reset or powering up the board. It is not run on soft reset, for example, if you reload the board from the serial console or the REPL. This is in contrast to the code within **code.py** , which is executed after CircuitPython is already running.
The **CIRCUITPY** drive is typically writable by your computer; this is what allows you to edit your code directly on the board. The reason you need a **boot.py** file is that you have to set the filesystem to be read-only by your computer to allow it to be writable by CircuitPython. This is because CircuitPython cannot write to the filesystem at the same time as your computer. Doing so can lead to filesystem corruption and loss of all content on the drive, so CircuitPython is designed to only allow one at at time.
Danger:
## boot.py
https://github.com/adafruit/Adafruit_Learning_System_Guides/blob/main/CircuitPython_Essentials/CircuitPython_Logger/boot.py
The `storage.remount()` command has a `readonly` keyword argument. **This argument refers to the read/write state of CircuitPython. ** It does NOT refer to the read/write state of your computer.
When the physical pin is connected to ground, it returns `False`. The `readonly` argument in boot.py is set to the `value` of the pin. When the `value=True`, the CIRCUITPY drive is read-only to CircuitPython (and writable by your computer). **When the `value=False`, the CIRCUITPY drive is writable by CircuitPython** (and read-only by your computer).
For **Gemma M0,** **Trinket M0, Metro M0 Express, Metro M4 Express, ItsyBitsy M0 Express and ItsyBitsy M4 Express** , no changes to the initial code are needed.
For **Feather M0 Express and Feather M4 Express** , comment out `switch = digitalio.DigitalInOut(board.D2)`, and uncomment `switch = digitalio.DigitalInOut(board.D5)`.
For **Circuit Playground Express and Circuit Playground Bluefruit** , comment out `switch = digitalio.DigitalInOut(board.D2)`, and uncomment `switch = digitalio.DigitalInOut(board.D7)`. Remember, D7 is the onboard slide switch, so there's no extra wires or alligator clips needed.
On the Circuit Playground Express or Circuit Playground Bluefruit, the switch is in the right position (closer to the ear icon on the silkscreen) it returns `False`, and the **CIRCUITPY** drive will be writable by CircuitPython. If the switch is in the left position (closer to the music icon on the silkscreen), it returns `True`, and the **CIRCUITPY** drive will be writable by your computer.
Info:
## Installing Project Code
In the example below, click the **Download Project Bundle** button below to download the necessary libraries and the **code.py** file in a zip file. Extract the contents of the zip file, open the directory **CircuitPython\_Essentials/CircuitPython\_Logger/** and then click on the directory that matches the version of CircuitPython you're using and copy the contents of that directory to your **CIRCUITPY** drive.
Your **CIRCUITPY** drive should now look similar to the following image:
https://github.com/adafruit/Adafruit_Learning_System_Guides/blob/main/CircuitPython_Essentials/CircuitPython_Logger/code.py
Info:
## Logging the Temperature
The way **boot.py** works is by checking to see if the pin you specified in the switch setup in your code is connected to a ground pin. If it is, it changes the read-write state of the file system, so the CircuitPython core can begin logging the temperature to the board.
For help finding the correct pins, see the wiring diagrams and information in the [Find the Pins section of the CircuitPython Digital In & Out guide](../../../../adafruit-trinket-m0-circuitpython-arduino/circuitpython-digital-in-out#find-the-pins). Instead of wiring up a switch, however, you'll be connecting the pin directly to ground with alligator clips or jumper wires.
Warning:
Once you copied the files to your board, eject it and unplug it from your computer. If you're using your Circuit Playground Express, all you have to do is make sure the switch is to the right. Otherwise, use alligator clips or jumper wires to connect the chosen pin to ground. Then, plug your board back into your computer.
You will not be able to edit code on your **CIRCUITPY** drive anymore!
The red LED should blink once a second and you will see a new **temperature.txt** file on **CIRCUITPY**.
This file gets updated once per second, but you won't see data come in live. Instead, when you're ready to grab the data, eject and unplug your board. For CPX, move the switch to the left, otherwise remove the wire connecting the pin to ground. Now it will be possible for you to write to the filesystem from your computer again, but it will not be logging data.
We have a more detailed guide on this project available here: [CPU Temperature Logging with CircuitPython](../../../../cpu-temperature-logging-with-circuit-python). If you'd like more details, check it out!
# Adafruit Circuit Playground Bluefruit
## Playground Temperature
Info:
But wait! There's more -- the Circuit Playground Express can also tell the temperature!
How, you ask? With a build in thermistor. This little sensor is a thermally sensitive resistor, meaning it's resistance changes based on temperature.
We can access its readings in CircuitPython by importing the **adafruit\_thermistor** library, and then using the `board.TEMPERATURE` pin to read the thermistor value.
In the example below, click the **Download Project Bundle** button below to download the necessary libraries and the **code.py** file in a zip file. Extract the contents of the zip file, open the directory **Introducing\_CircuitPlaygroundExpress/CircuitPlaygroundExpress\_Temperature/** and then click on the directory that matches the version of CircuitPython you're using and copy the contents of that directory to your **CIRCUITPY** drive.
Your **CIRCUITPY** drive should now look similar to the following image:
https://github.com/adafruit/Adafruit_Learning_System_Guides/blob/main/Introducing_CircuitPlaygroundExpress/CircuitPlaygroundExpress_Temperature/code.py
Then, open up a REPL session and you'll see the temperature readings in both Celsius and Fahrenheit.
Try placing your finger over the sensor (you'll see a thermometer icon on the board) and watch the readings change.
# Adafruit Circuit Playground Bluefruit
## Playground Light Sensor
Info:
The Circuit Playground Express can see you! OK, not really. That would be creepy.
But, it can sense light and dark, as well as colors and even your pulse!!
The Light Sensor in the upper left of the board (look for the eye icon) is a phototransistor. Here's how to use it as a light sensor:
In the example below, click the **Download Project Bundle** button below to download the necessary libraries and the **code.py** file in a zip file. Extract the contents of the zip file, open the directory **Introducing\_CircuitPlaygroundExpress/CircuitPlaygroundExpress\_LightSensor/** and then click on the directory that matches the version of CircuitPython you're using and copy the contents of that directory to your **CIRCUITPY** drive.
Your **CIRCUITPY** drive should now look similar to the following image:
https://github.com/adafruit/Adafruit_Learning_System_Guides/blob/main/Introducing_CircuitPlaygroundExpress/CircuitPlaygroundExpress_LightSensor/code.py
The ** ** code reads the light sensor and then lights up the NeoPixels like a bar graph depending on the light level. Try waving your hand over it, or shining it with a flashlight to see it change!
# Adafruit Circuit Playground Bluefruit
## Playground Drum Machine
Info:
A wise man once said, _ **"Nothing sounds better than an Eight-O-Eight."** _
(That wise man was Adam Horovitz of the Beastie Boys.)
The 808 to which Ad-Rock was referring is the Roland TR-808 drum machine. Let's build a little Circuit Playground Express tribute to the venerable 808! Instead of a full-blown drum pattern sequencer, we'll just focus on the machine's pads which are used for finger drumming to play back sampled drum sounds.
We can use the capacitive touch pads on the Circuit Playground Express as triggers, and small .wav files for our drum sounds!
## Installing Project Code
To use with CircuitPython, you need to first install a few libraries, into the lib folder on your **CIRCUITPY** drive. Then you need to update **code.py** with the example script.
Thankfully, we can do this in one go. In the example below, click the **Download Project Bundle** button below to download the necessary libraries and the **code.py** file in a zip file. Extract the contents of the zip file, open the directory **Introducing\_CircuitPlaygroundExpress/CircuitPlaygroundExpress\_808\_Drum\_Machine/** and then click on the directory that matches the version of CircuitPython you're using and copy the contents of that directory to your **CIRCUITPY** drive.
Your **CIRCUITPY** drive should now look similar to the following image:
https://github.com/adafruit/Adafruit_Learning_System_Guides/blob/main/Introducing_CircuitPlaygroundExpress/CircuitPlaygroundExpress_808_Drum_Machine/code.py
Try it out! When you tap the capacitive pads, the corresponding drum sample is triggered!!
Things are a bit crammed, admittedly, so you can try adding foil, copper tape, alligator clips, etc. in order to increase the surface area and physical space you have for your drumming!
Warning:
If you want to use your own sound files, you can! Record, sample, remix, or simply download files from a sound file sight, such as freesample.org. Then, to make sure you have the files converted to the proper specifications, [check out this guide here](../../../../adafruit-wave-shield-audio-shield-for-arduino/convert-files) that'll show you how! Spoiler alert: you'll need to make a small, 22Khz (or lower), 16 bit PCM, mono .wav file!
Want to listen to your Drum Machine at body movin' volumes? No problem! Hook up an [1/8"](https://www.adafruit.com/product/2790) or [1/4" phono output](https://www.adafruit.com/product/2911) to the **GND** and **A0/Audio** pads, then plug in to an amp!! I tried it on a small guitar amp and it sounds great.
https://www.youtube.com/watch?v=zLD_77xkrW4
# Adafruit Circuit Playground Bluefruit
## Playground Sound Meter
Info:
Use the microphone on your Circuit Playground Express to measure sound levels and display them on a VU-meter-like display!
The program is below. There are many settings that you can change to make the readings more or less sensitive and the display more or less jumpy. Try changing `CURVE` to be 4 or 1 or 10 or -2 and see what happens.
The program samples audio for a short time and the computes the energy in the sample (corresponding to volume) using a [Root-Mean-Square](https://en.wikipedia.org/wiki/Root_mean_square) computation (RMS). You could try varying the sample size if you like.
The` log_scale()` function varies the number of NeoPixels lit in an exponential way, because sound levels can vary by many factors of 10 between loud and soft. Try varying how it's computed to see what happens.
The program takes one sample when it first starts to set a "quiet" sound level. If that doesn't work for you, set `input_floor` to be a fixed number. If the meter seems too sensitive, try changing `input_ceiling = input_floor + ``500` to be `input_ceiling = input_floor + 2000` or higher. Or go the other way.
You can also change the colors. Try different ways of computing `volume_color(i)` for more of a rainbow effect, or make it a constant if you don't like changing colors.
## Installing Project Code
To use with CircuitPython, you need to first install a few libraries, into the lib folder on your **CIRCUITPY** drive. Then you need to update **code.py** with the example script.
Thankfully, we can do this in one go. In the example below, click the **Download Project Bundle** button below to download the necessary libraries and the **code.py** file in a zip file. Extract the contents of the zip file, open the directory **Introducing\_CircuitPlaygroundExpress\_SoundMeter/** and then click on the directory that matches the version of CircuitPython you're using and copy the contents of that directory to your **CIRCUITPY** drive.
Your **CIRCUITPY** drive should now look similar to the following image:
https://github.com/adafruit/Adafruit_Learning_System_Guides/blob/main/Introducing_CircuitPlaygroundExpress/CircuitPlaygroundExpress_SoundMeter/code.py
# Adafruit Circuit Playground Bluefruit
## Playground Color Picker
You can use your Circuit Playground Bluefruit with the [**Adafruit Bluefruit LE Connect**](https://learn.adafruit.com/adafruit-circuit-playground-bluefruit/bluefruit-le-connect) mobile app to control the NeoPixel RGB LEDs on the CPB!
## Installing Project Code
To use with CircuitPython, you need to first install a few libraries, into the lib folder on your **CIRCUITPY** drive. Then you need to update **code.py** with the example script.
Thankfully, we can do this in one go. In the example below, click the **Download Project Bundle** button below to download the necessary libraries and the **code.py** file in a zip file. Extract the contents of the zip file, open the directory **examples/** and then click on the directory that matches the version of CircuitPython you're using and copy the contents of that directory to your **CIRCUITPY** drive.
Your **CIRCUITPY** drive should now look similar to the following image:
https://github.com/adafruit/Adafruit_CircuitPython_BLE/blob/main/examples/ble_bluefruit_color_picker.py
Connect to your board through the Adafruit Bluefruit LE Connect mobile app. If you need assistance, [check out this page on installing and using the app](https://learn.adafruit.com/adafruit-circuit-playground-bluefruit/bluefruit-le-connect).
Once connected, from the device menu, tap on Controller, then Color Picker. Choose a color from the dial and tap Select (Android) or Send selected color (iOS). The LEDs will light up in the color you chose!
# Adafruit Circuit Playground Bluefruit
## Playground Bluetooth Plotter
The Circuit Playground Bluefruit has a built in light sensor that returns a light value and a temperature sensor that returns the temperature in degrees Celsius. The Adafruit Bluefruit LE Connect mobile app has a built in plotter function that you can use to plot any numerical information. This page will show you how to plot the light and temperature data from the Circuit Playground Bluefruit in the Bluefruit LE Connect app!
## Installing Project Code
To use with CircuitPython, you need to first install a few libraries, into the lib folder on your **CIRCUITPY** drive. Then you need to update **code.py** with the example script.
Thankfully, we can do this in one go. In the example below, click the **Download Project Bundle** button below to download the necessary libraries and the **code.py** file in a zip file. Extract the contents of the zip file, open the directory **examples/** and then click on the directory that matches the version of CircuitPython you're using and copy the contents of that directory to your **CIRCUITPY** drive.
Your **CIRCUITPY** drive should now look similar to the following image:
https://github.com/adafruit/Adafruit_CircuitPython_BLE/blob/main/examples/ble_bluefruit_connect_plotter.py
Connect to your board through the Adafruit Bluefruit LE Connect mobile app. If you need assistance, check out [the Bluefruit LE Connect Basics page in the Getting Started guide](https://learn.adafruit.com/circuitpython-nrf52840/bluefruit-le-connect-basics).
Once connected, tap Plotter.
Your data should start plotting automatically. Try shining a light towards your Circuit Playground Bluefruit to see the light value line change. Try placing your finger over the thermistor (towards the top-right, labeled A9, next to the picture of a thermometer) to see the temperature value line change.
That's all there is to plotting numerical data with the Circuit Playground Bluefruit and the Adafruit Bluefruit LE Connect mobile app!
# Adafruit Circuit Playground Bluefruit
## Arduino Support Setup
You can install the Adafruit Bluefruit nRF52 BSP (Board Support Package) in two steps:
Danger:
Danger:
# 1. BSP Installation
### Recommended: Installing the BSP via the Board Manager
- [Download and install the Arduino IDE](https://www.arduino.cc/en/Main/Software) (At least **v1.8** )
- Start the Arduino IDE
- Go into Preferences
- Add `https://adafruit.github.io/arduino-board-index/package_adafruit_index.json` as an ' **Additional Board Manager URL**' (see image below)
- Restart the Arduino IDE
- Open the **Boards Manager** option from the **Tools -\> Board** menu and install ' **Adafruit nRF52 by Adafruit**' (see image below)
It will take up to a few minutes to finish installing the cross-compiling toolchain and tools associated with this BSP.
**The delay during the installation stage shown in the image below is normal** , please be patient and let the installation terminate normally:
Once the BSP is installed, select
- **Adafruit Bluefruit nRF52832 Feather** (for the nRF52 Feather)
- **Adafruit Bluefruit nRF52840 Feather Express** (for the nRF52840 Feather)
- **Adafruit ItsyBitsy nRF52840** (for the Itsy '850)
- **Adafruit Circuit Playground Bluefruit** (for the CPB)
- etc...
from the **Tools -\> Board** menu, which will update your system config to use the right compiler and settings for the nRF52:
# 2. LINUX ONLY: adafruit-nrfutil Tool Installation
[adafruit-nrfutil](https://github.com/adafruit/Adafruit_nRF52_nrfutil) is a ** modified version** of [Nordic's nrfutil](https://github.com/NordicSemiconductor/pc-nrfutil), which is used to flash boards using the built in serial bootloader. It is originally written for Python 2, but have been migrated to Python 3 and renamed to **adafruit-nrfutil** since BSP version 0.8.5.
Warning:
Install Python 3 if it is not installed in your system already
```
$ sudo apt-get install python3
```
Then run the following command to install the tool from PyPi
```
$ pip3 install --user adafruit-nrfutil
```
Add pip3 installation dir to your **PATH** if it is not added already. Make sure adafruit-nrfutil can be executed in terminal by running
```
$ adafruit-nrfutil version
adafruit-nrfutil version 0.5.3.post12
```
# 3. Update the bootloader (nRF52832 ONLY)
To keep up with Nordic's SoftDevice advances, you will likely need to update your bootloader if you are using the original nRF52832 based **Bluefruit nRF52 Feather** boards.
Follow this link for instructions on how to do that
Info:
[Update the nRF52832 Bootloader](https://learn.adafruit.com/bluefruit-nrf52-feather-learning-guide/updating-the-bootloader)
# Advanced Option: Manually Install the BSP via 'git'
If you wish to do any development against the core codebase (generate pull requests, etc.), you can also optionally install the Adafruit nRF52 BSP manually using 'git', as decribed below:
### Adafruit nRF52 BSP via git (for core development and PRs only)
1. Install BSP via Board Manager as above to install compiler & tools.
2. Delete the core folder **nrf52** installed by Board Manager in Adruino15, depending on your OS. It could be
**macOS** : `~/Library/Arduino15/packages/adafruit/hardware/nrf52` **Linux** : `~/.arduino15/packages/adafruit/hardware/nrf52` **Windows** : `%APPDATA%\Local\Arduino15\packages\adafruit\hardware\nrf52`
3. Go to the sketchbook folder on your command line, which should be one of the following:
**macOS** : `~/Documents/Arduino` **Linux** : `~/Arduino` **Windows** : `~/Documents/Arduino`
4. Create a folder named `hardware/Adafruit`, if it does not exist, and change directories into it.
5. Clone the [Adafruit\_nRF52\_Arduino](https://github.com/adafruit/Adafruit_nRF52_Arduino) repo in the folder described in step 2:
`git clone --recurse-submodules git@github.com:adafruit/Adafruit_nRF52_Arduino.git`
6. This should result in a final folder name like `~/Documents/Arduino/hardware/Adafruit/Adafruit_nRF52_Arduino` (macOS).
7. Restart the Arduino IDE
# Adafruit Circuit Playground Bluefruit
## Arduino BLE Examples
There are numerous examples available for the Bluefruit nRF52/nRF52840 Feathers in the **Examples** menu of the nRF52 BSP, and these are always up to date. You're first stop looking for example code should be there:
# Example Source Code
The latest example source code is always available and visible on Github, and the public git repository should be considered the definitive source of example code for this board.
[Click here to browse the example source code on Github](https://github.com/adafruit/Adafruit_nRF52_Arduino/tree/master/libraries/Bluefruit52Lib/examples)
# Documented Examples
To help explain some common use cases for the nRF52 BLE API, feel free to consult the example documentation in this section of the learning guide:
- **Advertising: Beacon** - Shows how to use the BLEBeacon helper class to configure your Bleufruit nRF52 Feather as a beacon
- **BLE UART: Controller** - Shows how to use the **Controller** utility in our Bluefruit LE Connect apps to send basic data between your peripheral and your phone or tablet.
- **Custom: HRM** - Shows how to defined and work with a custom GATT Service and Characteristic, using the officially adopted Heart Rate Monitor (HRM) service as an example.
- **BLE Pin I/O** (StandardFirmataBLE) Shows how to control Pin I/O of nRF52 with Firmata protocol
For more information on the Arduino nRF52 API, check out [this page](https://learn.adafruit.com/bluefruit-nrf52-feather-learning-guide/bluefruit-nrf52-api).
# Adafruit Circuit Playground Bluefruit
## Advertising: Beacon
This example shows how you can use the BLEBeacon helper class and advertising API to configure your Bluefruit nRF52 board as a 'Beacon'.
# Complete Code
https://github.com/adafruit/Adafruit_nRF52_Arduino/blob/master/libraries/Bluefruit52Lib/examples/Peripheral/beacon/beacon.ino
The **bluefruit.h** file is below (which includes the `Bluefruit.setTxPower()` allowed values.
https://github.com/adafruit/Adafruit_nRF52_Arduino/blob/master/libraries/Bluefruit52Lib/src/bluefruit.h
# Output
You can use the nRF Beacons application from Nordic Semiconductors to test this sketch:
- [nRF Beacons for iOS](https://itunes.apple.com/app/nrf-beacons/id879614768?mt=8)
- [nRF Beacons for Android](https://play.google.com/store/apps/details?id=no.nordicsemi.android.nrfbeacon)
Make sure that you set the UUID, Major and Minor values to match the sketch above, and then run the sketch at the same time as the nRF Beacons application.
With the default setup you should see a Mona Lisa icon when the beacon is detected. If you don't see this, double check the UUID, Major and Minor values to be sure they match exactly.
# Adafruit Circuit Playground Bluefruit
## BLE UART: Controller
This examples shows you you can use the BLEUart helper class and the Bluefruit LE Connect applications to send based keypad and sensor data to your nRF52.
# Setup
In order to use this sketch, you will need to open Bluefruit LE Connect on your mobile device using our free [iOS](https://itunes.apple.com/app/adafruit-bluefruit-le-connect/id830125974?mt=8), [Android](https://play.google.com/store/apps/details?id=com.adafruit.bluefruit.le.connect) or [OS X](https://itunes.apple.com/us/app/adafruit-bluefruit-le-connect/id1082414600?mt=12) applications.
- Load the [**Controller** example sketch](https://github.com/adafruit/Adafruit_nRF52_Arduino/tree/master/libraries/Bluefruit52Lib/examples/Peripheral/controller) in the Arduino IDE
- Compile the sketch and flash it to your nRF52 based Feather
- Once you are done uploading, open the **Serial Monitor** (Tools \> Serial Monitor)
- Open the **Bluefruit LE Connect** application on your mobile device
- Connect to the appropriate target (probably ' **Bluefruit52**')
- Once connected switch to the **Controller** application inside the app
- Enable an appropriate control surface. The **Color Picker** control surface is shown below, for example (screen shot taken from the iOS application):
As you change the color (or as other data becomes available) you should receive the data on the nRF52, and see it in the Serial Monitor output:
# Complete Code
https://github.com/adafruit/Adafruit_nRF52_Arduino/blob/master/libraries/Bluefruit52Lib/examples/Peripheral/controller/controller.ino
You will also need the following helper class in a file called **packetParser.cpp** :
https://github.com/adafruit/Adafruit_nRF52_Arduino/blob/master/libraries/Bluefruit52Lib/examples/Peripheral/controller/packetParser.cpp
# Adafruit Circuit Playground Bluefruit
## Custom: HRM
The BLEService and BLECharacteristic classes can be used to implement any custom or officially adopted BLE service of characteristic using a set of basic properties and callback handlers.
The example below shows how to use these classes to implement the [Heart Rate Monitor](https://www.bluetooth.com/specifications/gatt/viewer?attributeXmlFile=org.bluetooth.service.heart_rate.xml) service, as defined by the Bluetooth SIG.
# HRM Service Definition
**UUID** : [0x180D](https://www.bluetooth.com/specifications/gatt/viewer?attributeXmlFile=org.bluetooth.service.heart_rate.xml)
Only the first characteristic is mandatory, but we will also implement the optional **Body Sensor Location** characteristic. Heart Rate Control Point won't be used in this example to keep things simple.
# Implementing the HRM Service and Characteristics
The core service and the first two characteristics can be implemented with the following code:
First, define the BLEService and BLECharacteristic variables that will be used in your project:
```
/* HRM Service Definitions
* Heart Rate Monitor Service: 0x180D
* Heart Rate Measurement Char: 0x2A37
* Body Sensor Location Char: 0x2A38
*/
BLEService hrms = BLEService(UUID16_SVC_HEART_RATE);
BLECharacteristic hrmc = BLECharacteristic(UUID16_CHR_HEART_RATE_MEASUREMENT);
BLECharacteristic bslc = BLECharacteristic(UUID16_CHR_BODY_SENSOR_LOCATION);
```
Then you need to 'populate' those variables with appropriate values. For simplicity sake, you can define a custom function for your service where all of the code is placed, and then just call this function once in the 'setup' function:
```
void setupHRM(void)
{
// Configure the Heart Rate Monitor service
// See: https://www.bluetooth.com/specifications/gatt/viewer?attributeXmlFile=org.bluetooth.service.heart_rate.xml
// Supported Characteristics:
// Name UUID Requirement Properties
// ---------------------------- ------ ----------- ----------
// Heart Rate Measurement 0x2A37 Mandatory Notify
// Body Sensor Location 0x2A38 Optional Read
// Heart Rate Control Point 0x2A39 Conditional Write <-- Not used here
hrms.begin();
// Note: You must call .begin() on the BLEService before calling .begin() on
// any characteristic(s) within that service definition.. Calling .begin() on
// a BLECharacteristic will cause it to be added to the last BLEService that
// was 'begin()'ed!
// Configure the Heart Rate Measurement characteristic
// See: https://www.bluetooth.com/specifications/gatt/viewer?attributeXmlFile=org.bluetooth.characteristic.heart_rate_measurement.xml
// Permission = Notify
// Min Len = 1
// Max Len = 8
// B0 = UINT8 - Flag (MANDATORY)
// b5:7 = Reserved
// b4 = RR-Internal (0 = Not present, 1 = Present)
// b3 = Energy expended status (0 = Not present, 1 = Present)
// b1:2 = Sensor contact status (0+1 = Not supported, 2 = Supported but contact not detected, 3 = Supported and detected)
// b0 = Value format (0 = UINT8, 1 = UINT16)
// B1 = UINT8 - 8-bit heart rate measurement value in BPM
// B2:3 = UINT16 - 16-bit heart rate measurement value in BPM
// B4:5 = UINT16 - Energy expended in joules
// B6:7 = UINT16 - RR Internal (1/1024 second resolution)
hrmc.setProperties(CHR_PROPS_NOTIFY);
hrmc.setPermission(SECMODE_OPEN, SECMODE_NO_ACCESS);
hrmc.setFixedLen(2);
hrmc.setCccdWriteCallback(cccd_callback); // Optionally capture CCCD updates
hrmc.begin();
uint8_t hrmdata[2] = { 0b00000110, 0x40 }; // Set the characteristic to use 8-bit values, with the sensor connected and detected
hrmc.notify(hrmdata, 2); // Use .notify instead of .write!
// Configure the Body Sensor Location characteristic
// See: https://www.bluetooth.com/specifications/gatt/viewer?attributeXmlFile=org.bluetooth.characteristic.body_sensor_location.xml
// Permission = Read
// Min Len = 1
// Max Len = 1
// B0 = UINT8 - Body Sensor Location
// 0 = Other
// 1 = Chest
// 2 = Wrist
// 3 = Finger
// 4 = Hand
// 5 = Ear Lobe
// 6 = Foot
// 7:255 = Reserved
bslc.setProperties(CHR_PROPS_READ);
bslc.setPermission(SECMODE_OPEN, SECMODE_NO_ACCESS);
bslc.setFixedLen(1);
bslc.begin();
bslc.write8(2); // Set the characteristic to 'Wrist' (2)
}
```
## Service + Characteristic Setup Code Analysis
1. The first thing to do is to call **.begin()** on the BLEService ( **hrms** above). Since the UUID is set in the object declaration at the top of the sketch, there is normally nothing else to do with the BLEService instance.
Danger:
2. Next, you can configure the **Heart Rate Measurement** characteristic ( **hrmc** above). The values that you set for this will depend on the characteristic definition, but for convenience sake we've documented the key information in the comments in the code above.
- '`hrmc.setProperties(CHR_PROPS_NOTIFY);`' - This sets the PROPERTIES value for the characteristic, which determines how the characteristic can be accessed. In this case, the Bluetooth SIG has defined the characteristic as **Notify** , which means that the peripheral will receive a request ('notification') from the Central when the Central wants to receive data using this characteristic.
- ``hrmc.setPermission(SECMODE_OPEN, SECMODE_NO_ACCESS);`` - This sets the security for the characteristic, and should normally be set to the values used in this example.
- ``hrmc.setFixedLen(2);`` - This tells the Bluetooth stack how many bytes the characteristic contains (normally a value between 1 and 20). In this case, we will use a fixed size of two bytes, so we call **.setFixedLen**. If the characteristic has a variable length, you would need to set the max size via **.setMaxLen**.
- '`hrmc.setCccdWriteCallback(cccd_callback);`' - This optional code sets the callback that will be fired when the CCCD record is updated by the central. This is relevant because the characteristic is setup with the NOTIFY property. When the Central sets to 'Notify' bit, it will write to the CCCD record, and you can capture this write even in the CCCD callback and turn the sensor on, for example, allowing you to save power by only turning the sensor on (and back off) when it is or isn't actually being used. For the implementation of the CCCD callback handler, see the full sample code at the bottom of this page.
- '`hrmc.begin();`' Once all of the properties have been set, you must call **.begin()** which will add the characteristic definition to the last BLEService that was '.begin()ed'.
3. Optionally set an initial value for the characteristic(s), such as the following code that populates 'hrmc' with a correct values, indicating that we are providing 8-bit heart rate monitor values, that the Body Sensor Location characteristic is present, and setting the first heart rate value to 0x04:
Info:
```
// Set the characteristic to use 8-bit values, with the sensor connected and detected
uint8_t hrmdata[2] = { 0b00000110, 0x40 };
// Use .notify instead of .write!
hrmc.notify(hrmdata, 2);
```
The CCCD callback handler has the following signature:
```
void cccd_callback(uint16_t conn_hdl, BLECharacteristic* chr, uint16_t cccd_value)
{
// Display the raw request packet
Serial.print("CCCD Updated: ");
//Serial.printBuffer(request->data, request->len);
Serial.print(cccd_value);
Serial.println("");
// Check the characteristic this CCCD update is associated with in case
// this handler is used for multiple CCCD records.
if (chr->uuid == htmc.uuid) {
if (chr->indicateEnabled(conn_hdl)) {
Serial.println("Temperature Measurement 'Indicate' enabled");
} else {
Serial.println("Temperature Measurement 'Indicate' disabled");
}
}
}
```
4. Repeat the same procedure for any other BLECharacteristics in your service.
# Full Sample Code
The full sample code for this example can be seen below:
https://github.com/adafruit/Adafruit_nRF52_Arduino/blob/master/libraries/Bluefruit52Lib/examples/Peripheral/custom_hrm/custom_hrm.ino
# Adafruit Circuit Playground Bluefruit
## Bluefruit LE Connect
The **Bluefruit LE Connect** app provides iOS devices with a variety of tools to communicate with Bluefruit LE devices, such as the **Circuit Playground Bluefruit**! These tools cover basic communication and info reporting as well as more project specific uses such as remote button control and a NeoPixel color picker.
The iOS app is a [free download from Apple's App Store](https://itunes.apple.com/us/app/adafruit-bluefruit-le-connect/id830125974?mt=8 "Bluefruit LE Connect"). As of this writing, it requires iOS 11.3 or later and works on the **iPhone** , **iPad** , and **iPod Touch**.
## Install Bluefruit LE
The first step is to install the app on your device.
## Enable Bluetooth
If Bluetooth is disabled on your device, enable it by going to **Setting \> Bluetooth** on your iOS device and then turning it on.
## Enable Location Services
If you plan to use the app to send location/GPS data to Bluefruit LE, enable Location Services. Enable it on iOS using **Settings-\>Privacy-\>Location Services**.
## Scan for Devices
Launch the app now -- it will automatically begin to scan the airwaves for Bluetooth LE devices. These are presented in a list at the bottom of the page.
Notice, you can use the **Must have UART Service** filter to prevent BLE devices from showing up that can't work with the app.
- To refresh the list and start a new scan, simply swipe down on the current list.
- Each device's signal strength is displayed in the left side of its row.
If you tap on the device entry (not on **Connect** ), you'll see more detail about a particular device:
## Connect
Tap the **Connect** button on the UART capable device you wish to use. The app will connect to the Circuit Playground Bluefruit! Now, you'll be presented with the Device name and signal strength, and a number of different Modules you can use.
## Controller Module
Click on the **Controller** module. You'll see a number of different sensor data streaming options. Enabling these will allow you to send data from your phone, such as the **Accelerometer** data or **Location** data, directly to your Circuit Playground Bluefruit!
The two modules on this page that can send data to the Circuit Playground Bluefruit are the **Control Pad** and **Color Picker.**
## Color Picker
Click on the **Color Picker.** Now, you can dial in the hue, saturation, and value of a color using the color wheel and value slider.
[Follow this page](https://learn.adafruit.com/adafruit-circuit-playground-bluefruit/playground-color-picker) for setting up the CPB with the color picker code.
Press the **Send selected color** button and your color values will be sent to the Circuit Playground Bluefruit to adjust its NeoPixels!
The app provides many other features with the additional modules. Have a look at the [Bluefruit LE Connect for iOS and Android standalone guide](https://learn.adafruit.com/bluefruit-le-connect/features) for an explanation of each feature.
# Adafruit Circuit Playground Bluefruit
## Downloads
## Files:
- [Datasheet for Nordic nRF52840](https://infocenter.nordicsemi.com/pdf/nRF52840_PS_v1.1.pdf)
- [Nordic InfoCenter for further documentation](https://infocenter.nordicsemi.com/index.jsp)
- [EagleCAD files for Circuit Playground Bluefruit on GitHub](https://github.com/adafruit/Adafruit-Circuit-Playground-Bluefruit-PCB)
- [3D Models on GitHub](https://github.com/adafruit/Adafruit_CAD_Parts/tree/master/4333%20Circuit%20Playground%20Bluefruit)
- [Fritzing object in the Adafruit Fritzing Library](https://github.com/adafruit/Fritzing-Library/blob/master/parts/Adafruit%20Circuit%20Playground%20Bluefruit.fzpz)
- [PDF for Circuit Playground Bluefruit PrettyPins Pinout Diagram](https://github.com/adafruit/Adafruit-Circuit-Playground-Bluefruit-PCB/blob/master/Adafruit%20Circuit%20Playground%20Bluefruit%20pinout.pdf)
[SVG for Circuit Playground Bluefruit PrettyPins Pinout Diagram](https://cdn-learn.adafruit.com/assets/assets/000/110/609/original/Adafruit_Circuit_Playground_Bluefruit_pinout.svg?1649358140)
To download the original Circuit Playground Bluefruit sketch that shipped on your CPB, click the button below.
[CPBLUEFRUIT.UF2](https://cdn-learn.adafruit.com/assets/assets/000/101/989/original/CPBLUEFRUIT.UF2?1620059549)
# Schematic for Circuit Playground Bluefruit
# Fab print of Circuit Playground Bluefruit
## Primary Products
### Circuit Playground Bluefruit - Bluetooth® Low Energy
[Circuit Playground Bluefruit - Bluetooth® Low Energy](https://www.adafruit.com/product/4333)
**Circuit Playground Bluefruit** is our third board in the Circuit Playground series, another step towards a perfect introduction to electronics and programming. We've taken the popular Circuit Playground Express and made it even better! Now the main chip is an nRF52840...
Out of Stock
[Buy Now](https://www.adafruit.com/product/4333)
[Related Guides to the Product](https://learn.adafruit.com/products/4333/guides)
## Featured Products
### Lithium Ion Polymer Battery - 3.7v 500mAh
[Lithium Ion Polymer Battery - 3.7v 500mAh](https://www.adafruit.com/product/1578)
Lithium-ion polymer (also known as 'lipo' or 'lipoly') batteries are thin, light, and powerful. The output ranges from 4.2V when completely charged to 3.7V. This battery has a capacity of 500mAh for a total of about 1.9 Wh. If you need a larger (or smaller!) battery,
Out of Stock
[Buy Now](https://www.adafruit.com/product/1578)
[Related Guides to the Product](https://learn.adafruit.com/products/1578/guides)
### Adafruit Circuit Playground Bluefruit Express Starter Kit
[Adafruit Circuit Playground Bluefruit Express Starter Kit](https://www.adafruit.com/product/4504)
If you missed out on ADABOX 014, its not too late for you to pick up the parts necessary to build many of the projects! This kit pack doesn't come with tissue paper or the nifty extras, but it does have all the electronic goodies you need
This project pack features...
Out of Stock
[Buy Now](https://www.adafruit.com/product/4504)
[Related Guides to the Product](https://learn.adafruit.com/products/4504/guides)
## Related Guides
- [Now Playing: Bluetooth Apple Media Service Display](https://learn.adafruit.com/now-playing-bluetooth-apple-media-service-display.md)
- [Bluetooth Turtle Bot with CircuitPython and Crickit](https://learn.adafruit.com/bluetooth-turtle-bot-with-circuitpython-and-crickit.md)
- [Getting Started with CircuitPython and Bluetooth Low Energy](https://learn.adafruit.com/circuitpython-nrf52840.md)
- [TensorFlow Lite for Circuit Playground Bluefruit Quickstart](https://learn.adafruit.com/tensorflow-lite-for-circuit-playground-bluefruit-quickstart.md)
- [BLE Volume Knob with CircuitPython](https://learn.adafruit.com/bluetooth-le-hid-volume-knob-with-circuitpython.md)
- [TFT Gizmo Turtle](https://learn.adafruit.com/tft-gizmo-turtle.md)
- [Circuit Playground Bluetooth Cauldron](https://learn.adafruit.com/cpx-cauldron.md)
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- [No-Solder PaperCraft Crystal Light Strand](https://learn.adafruit.com/no-solder-papercraft-crystal-light-strand.md)
- [Cyberpunk Santa Eye](https://learn.adafruit.com/cyberpunk-santa-eye.md)
- [Bluefruit Playground Hide and Seek](https://learn.adafruit.com/hide-n-seek-bluefruit-ornament.md)
- [File Glider](https://learn.adafruit.com/file-glider.md)
- [CLUE Metal Detector in CircuitPython](https://learn.adafruit.com/clue-metal-detector-circuitpython.md)