Adafruit MPR121 12-Key Capacitive Touch Sensor Gator Breakout - STEMMA QT / Qwiic

Add lots of touch sensors to your next microcontroller project with this easy-to-use 12-channel capacitive touch sensor breakout board, starring the MPR121. This chip can handle up to 12 individual touchpads with a plug-and-play STEMMA QT connector and large alligator/croc-clip friendly pads, providing a no-solder solution to capacitive touch sensing.

The MPR121 supports reading data over I2C, which can be implemented with nearly any microcontroller. You can select one of 2 addresses via the ADDR pin, allowing up to 24 capacitive touch pads on one I2C 2-wire bus. This chip handles filtering and sensitivity configuration, making capacitive sensing easier than using analog inputs.

This sensor comes as a tiny hard-to-solder chip mounted on a breakout board. Since it's a 3V-only chip, a 3V regulator and I2C level shifting are included, making it safe to use with any 3V or 5V microcontroller/processor like Arduino. An LED on the IRQ line blinks when touches are detected, assisting with debugging.

The breakout features the STEMMA QT form factor with support circuitry, allowing use with a breadboard or SparkFun qwiic compatible STEMMA QT connectors and compatibility with 3.3V and 5V logic levels. (QT cables are sold separately.)

Getting started is simple with Arduino and CircuitPython libraries and tutorials available, enabling quick setup and easy porting to other microcontrollers.

Recommended conductive materials include copper foil, metallic nylon, or pyralux, connected to the breakout's large pads via alligator clips.