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.

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

sensor-breakout-tutorial

Page 4 of 20