Blink a LED
One of the first programs you typically write to get used to embedded programming is a sketch that repeatably blinks an LED. IoT projects are wireless so after completing this section, you'll be able to turn on (or off) the LED built into your board from anywhere in the world.
Navigate to io.adafruit.com/wippersnapper. You should see the board you just connected to Adafruit IO listed on this page.
- If you do not see your board - go back to the previous setup page and ensure you have registered it with Adafruit IO
Make sure the board's tile says Online in green text, indicating that it's online and communicating with Adafruit IO.
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If the board appears offline on the website but was previously connected, press the Reset (RST) button (or unplug the USB, and plug it back in) to force the board to reboot.
Click the board to navigate to its page.
From the device page, click the + New Component (or +) button.
The Component Picker lists all the sensors and actuators which can be used with the WipperSnapper firmware.
Click the LED icon.
Microcontroller boards contain GPIO pins that can be configured either as an input or an output. The "Create LED Component" screen tells WipperSnapper to configure a general-purpose output pin connected to the LED on your board as a digital output so you can turn the LED on or off.
The Raspberry Pi Pico W has a built-in LED. Select this pin as the LED Pin and click Create Component.
Behind the scenes, Adafruit IO sends send a command to your board running WipperSnapper telling it to configure the GPIO pin as a digital output.
Your board's page on Adafruit IO shows a new LED component.
On the board page, toggle the LED component by clicking the toggle switch. This should turn your board's built-in LED on or off.
Read a Push-Button
You can also configure a board running WipperSnapper to read data from standard input buttons, switches, or digital sensors, and send the value to Adafruit IO.
Let's wire up a push button to your board and configure it to publish a value to Adafruit IO when the button has been pressed or released.
From the component picker, select the Push Button.
The next screen presents you with options for configuring the push button. Start by selecting the board's pin you connected to the push button.
The Return Interval dictates how frequently the value of the push-button will be sent from the board to Adafruit IO.
For this example, you will configure the push button's value to be only sent when the value changes (i.e: when it's either pressed or depressed).
Select On Change
Finally, check the Specify Pin Pull Direction checkbox and select Pull UP to turn on the pin's internal pull-up resistor.
Make sure the form's settings look like the following screenshot. Then, click Create Component.
Adafruit IO sends a command to your WipperSnapper board, telling it to configure the GPIO pin you selected to behave as a digital input pin and to enable it to pull up the internal resistor. Your board's page should also show the new push-button component.
Push the button to change the value of the component on Adafruit IO.
Read an I2C Sensor
Inter-Integrate Circuit, aka I2C, is a two-wire protocol for connecting sensors and "devices" to a microcontroller. A large number of sensors, including the ones sold by Adafruit, use I2C to communicate.
Typically, using I2C with a microcontroller involves programming. Adafruit IO and WipperSnapper let you configure a microcontroller to read data from an I2C sensor and publish that data to the internet without writing code.
The WipperSnapper firmware supports a number of I2C sensors, viewable in list format here. If you do not see the I2C sensor you're attempting to use with WipperSnapper - we have a guide on adding a component to Adafruit IO WipperSnapper here.
The process for adding an I2C component to your board running WipperSnapper is similar for most sensors. For this section, we're using the Adafruit AHT20, an inexpensive sensor that can read ambient temperature and humidity.
Wiring
First, wire up an AHT20 sensor to your board exactly as follows. Here is an example of the AHT20 wired using I2C with a STEMMA QT cable (no soldering required).
While the Raspberry Pi Pico is able to define any two pins as an I2C bus, only an I2C bus using pins GPIO 4 and GPIO 5 is supported while using WipperSnapper.
To simplify wiring, we highly suggest using an Adafruit PiCowbell Proto for Pico since it includes a STEMMA QT/Qwiic connector for I2C.
- Before wiring everything up, follow the assembly page here to connect the PiCowbell to the Raspberry Pi Pico W.
Connect a "STEMMA QT to STEMMA QT" cable from the STEMMA QT port on the PiCowbell to a STEMMA QT port on your sensor.
If you do not have a PiCowBell, make the following connections between the Pico W and the AHT20:
- Pico 3.3V (Physical Pin 36) to AHT20 VIN
- Pico Ground to AHT20 GND
- Pico SCL (Physical Pin 5) to AHT20 SCL
- Pico SDA (Physical Pin 4) to AHT20 SDA
Scan I2C Bus
First, ensure that you've correctly wired the AHT20 sensor to your board by performing an I2C scan to detect the I2C device on the bus.
On the board page, click Start I2C Scan.
- If you do not see this button, double-check that your board shows as Online.
You should see a new pop-up showing a list of the I2C addresses detected by an I2C scan. If wired correctly, the AHT20's default I2C address of 0x38 appear in the I2C scan list.
First, double-check the connection and/or wiring between the sensor and the board.
Then, reset the board and let it re-connect to Adafruit IO WipperSnapper.
Create the Sensor Component
Now that you know the sensor can be detected by the board, it's time to configure and create the sensor on Adafruit IO.
On the board page, add a new component to your board by clicking the + button or the + New Component button.
The Component Picker lists all the available components, sensors, and parts that can be used with WipperSnapper.
Under the I2C Components header, click AHT20.
On the component configuration page, the AHT20's I2C sensor address should be listed along with the sensor's settings.
The AHT20 sensor can measure ambient temperature and relative humidity. This page has individual options for reading the ambient temperature, in either degree Celsius or degree Fahrenheit, and the relative humidity. You may select the readings which are appropriate to your application and region.
The Send Every option is specific to each sensor measurement. This option will tell the Feather how often it should read from the AHT20 sensor and send the data to Adafruit IO. Measurements can range from every 30 seconds to every 24 hours.
For this example, set the Send Every interval for both seconds to Every 30 seconds and click Create Component.
The board page should now show the AHT20 component you created.
After the interval you configured elapses, WipperSnapper automatically reads values from the sensor and sends them to Adafruit IO.
Going Further
Want to learn more about Adafruit IO WipperSnapper? We have more complex projects on the Adafruit Learning System.
Page last edited March 08, 2024
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