The MPR121 is a capacitive touch sensor controller driven by an I2C interface. The chip can control up to twelve individual electrodes, as well as a simulated thirteenth electrode The MPR121 also features eight LED driving pins. When these pins are not configured as electrodes, they may be used to drive LEDs There is no regulation on the board, so the voltage supplied should be between 2.5 and 3.6VDC Size: 3cm x 2cm