Datasheet

The MPR121 has support for only I2C, which can be implemented with nearly any microcontroller. You can select one of

4 addresses with the ADDR pin, for a total of 48 capacitive touch pads on one I2C 2-wire bus. Using this chip is a lot

easier than doing the capacitive sensing with analog inputs: it handles all the filtering for you and can be configured for

more/less sensitivity.

This sensor comes as a tiny hard-to-solder chip so we put it onto a breakout board for you. Since it's a 3V-only chip,

we added a 3V regulator and I2C level shifting so its safe to use with any 3V or 5V microcontroller/processor like

Arduino. We even added an LED onto the IRQ line so it will blink when touches are detected, making debugging by

sight a bit easier on you. Comes with a fully assembled board, and a stick of 0.1" header so you can plug it into a

breadboard. For contacts, we suggest using copper foil or pyralux, then solder a wire that connects from the foil pad to

the breakout.

https://learn.adafruit.com/adafruit-mpr121-12-key-capacitive-touch-sensor-breakout-

tutorial

Page 4 of 24