MPR121 Hookup Guide

Contributors: Toni_K


Capacitive Touch Keypad

The Capacitive Touch Keypad is very similar to the MPR121 breakout board, but instead of having to attach your own electrodes, this board comes with a 12-pin keypad built-in.


The keypad has 5 lines that need to be connected to your microcontroller, including the power lines, the IRQ line and the I2C lines.


MPR121 Keypad → Arduino Uno

  • 3.3V → 3.3V
  • SCL → A5
  • SDA → A4
  • GND → GND
  • IRQ → D2

Check out the Fritzing diagram below to verify your connections.

MPR121 Keypad Hookup

This diagram shows the bottom side of the keypad, in order to show you the location of the I2C address jumper. In this diagram, the jumper is set to 0, but if you need to have 2 keypads on the same I2C bus, you can change one of them to be set to 1.

Now that you’ve got your keypad hooked up properly, let’s get communicating with it!

Want more information about SparkFun's classes? Interested in getting involved with teaching electronics? Just want to talk? Sign up for our newsletter, or contact our education department.

SparkFun is a company built around one core idea – sharing ingenuity. We think everyone should have the hardware and resources to learn and play with cool electronic gadgetry.

Share, give, learn, SparkFun.

Do you regularly instruct classes and workshops in a formal or informal learning environment? SparkFun offers Educator Discounts to people teaching and sharing electronics.

Find out more.