The MPR121 capacitive keypad uses the MPR121 and 12 touch sensitive pads to give you a simple 'keypad' with an I2C output. The board also has four mounting holes allowing it to be used as an input system in place of traditional buttons. Check the example code below for an easy way to read the keypad.
Note: This keypad outputs 3.3V logic. If you are using a board which only accepts 5V logic, you will run into a problem. You will want to use a logic level converter, or a board which accepts 3.3V logic.
MPR121 Capacitive Touch Keypad Shield module sensitive key keyboard For arduino