The MacroPad is packed with onboard hardware, but what if you want to use it with even more hardware? The answer is to use the STEMMA QT port, located on the back left-hand side of the MacroPad underneath the OLED screen. 

I2C Devices

The STEMMA QT port is best for use with I2C devices. You can use any of the Qwiic-compatible I2C breakout boards available by plugging them into this port and coding them with either the available CircuitPython or Arduino drivers and libraries.

An I2C to GPIO Expander board may be added for more discrete GPIO pin availability if more than two GPIO are needed. An example:

Adafruit PCF8574 I2C GPIO Expander Breakout connected to a QTPY displaying a hand clicking a button which lights up a red LED.
Expand your project possibilities, with the Adafruit PCF8574 GPIO Expander Breakout - an affordable 8 channel I2C expander.GPIO expanders...
In Stock
Angled shot of STEMMA QT / Qwiic JST SH 4-pin Cable.
This 4-wire cable is a little over 100mm / 4" long and fitted with JST-SH female 4-pin connectors on both ends. Compared with the chunkier JST-PH these are 1mm pitch instead of...
Out of Stock


You can use either of the SCL and SDA pins from the STEMMA QT port as discreet GPIO, as long as they are not sharing a bus.

For example, you could connect a button's input to SDA and an LED's anode to SCL, with the STEMMA port's GND connecting to both components. In CircuitPython, these pins are accessed with board.SDA and board.SCL. In Arduino, SDA is pin 20 and SCL is pin 21.

It is not possible to add BLE or WiFi at this time to the MacroPad.

This guide was first published on Jun 30, 2021. It was last updated on Sep 14, 2022.

This page (Attaching External Hardware ) was last updated on Sep 14, 2022.

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