Power Pins

  • 3V - this is the regulated output from the onboard regulator. You can draw 500mA
  • 5V - This is 5v out from the USB port. You can also use this as a voltage input but you must have some sort of diode (schottky, signal, power, really anything) between your external power source and this pin with anode to battery, cathode to 5V pin
  • GND - Power/data/signal ground

Input/Output Pins

 

General Purpose / Analog Inputs

  • A0 / D0 - Digital/analog GPIO pin 0. Can act as a true analog output with 10 bit precision, but does not have PWM. Can also be a capacitive touch input.
  • A1 / D1 - Digital/analog GPIO pin 1. Can be a capacitive touch input or an AREF pin.
  • A2 / D2 - Digital/analog GPIO pin 2. Can act as PWM or capacitive touch input.
  • A3 / D3 - Digital/analog GPIO pin 3. Can act as PWM or capacitive touch input.

I2C Pins

  • SDA / D4 - This is the I2C data pin and digital pin 4, can also be a PWM. There is no analog on this pin! There's no pull up on this pin by default so when using with I2C, you may need a 2.2K-10K pullup on each to 3.3V. All our STEMMA QT breakouts have the pullup installed on the breakout PCB.
  • SCL / D5 - This is the I2C clock pin and digital pin 5, can also be a PWM. There is no analog on this pin! There's no pull up on this pin by default so when using with I2C, you may need a 2.2K-10K pullup on each to 3.3V

STEMMA QT - This connector allows you to connect over I2C (without soldering!) to breakout boards with STEMMA QT connectors or to other things with various associated accessories

Hardware Serial Pins

  • TX / A6 / D6 - Transmit (output) for Serial1. Also analog/digital GPIO 6. Can act as PWM or capacitive touch input.
  • RX / A7 / D7 - Receive (input) for Serial1. Also analog/digital GPIO 7. Can act as PWM or capacitive touch input.

SPI Pins

  • SCK / A8 / D8 - Hardware SPI clock pin. Also analog/digital GPIO 8. Can act as PWM output.
  • MI / A9 / D9 -  Hardware SPI MISO microcontroller in serial out pin. Also analog/digital GPIO 9. Can act as PWM output.
  • MO / A10 / D10 - Hardware SPI MOSI microcontroller out serial in pin. Also analog/digital GPIO 10. Can act as PWM output.

Onboard Neopixel pins

There is a very tiny NeoPixel that is connected to digital pin 11 for signal. If you would like to turn off the pixel for low power usage, set pin 12 low. By default pin 12 is set high for you by Arduino/CircuitPython

Capacitive touch pins

A0, A1, A2, A3, A6 (TX), A7 (RX) can be capacitive touch pins without the need for a separate driver pin.

Analog output pin

Only A0 can be a true analog output (not PWM!) at 10-bit resolution

Analog input pins

All pins except for SDA/SCL can be analog inputs with 12-bit read resolution

PWM output pins

Only A0 and A1 cannot be PWM output

I2S pins

  • Data pin is RX
  • Bit Clock pin is MOSI
  • Word Select pin is SCK

Only one data pin is available so you cannot have both I2S input and output.

Reverse Side SPI FLASH

The QT Py microcontroller has 256KB flash for storage of code and code-embedded files. In Circuitpython you will get a very small (~48KB) disk drive for your Python code storage. But, say you want more! You can solder a chip onto the back of the QT Py to add 2MB of SPI Flash storage.

These little chips are like miniature SSD drives for your electronics. When you don't need something with as much storage as a micro SD card, but an EEPROM is too small, SPI (or...
Out of Stock

Once soldered in, you can access the SPI flash in Arduino on SPI1 and chip select pin 17. In CircuitPython, a 'haxpress' version of the runtime will need to be installed, so it knows to look for the larger filesystem. There is more hardware support in the haxpress CircuitPython build because we can add more code to the internal flash instead of using it for a filesystem

This guide was first published on Sep 30, 2020. It was last updated on Sep 30, 2020.

This page (Pinouts) was last updated on Nov 06, 2020.