The examples in this guide are no longer supported. Check out the MPR121 sensor guide for CircuitPython and Python usage:

Reach out and touch somebody or some thing with capacitive touch sensing and the MPR121 capacitive touch breakout board.  Capacitive touch sensing means detecting when something conductive is touched by a large object or person.  For example detecting when a person touches a piece of foil, conductive ink, or even a piece of fruit or a vegetable.  It almost seems like magic but capacitive touch sensing is based on a very simple principle--by touching an object your body slightly changes the capacitance of it and that change can be detected with special circuitry.

The MPR121 board is a dedicated capacitive touch sensing chip that can check up to 12 inputs independently for touches.  Since the MPR121 uses a simple I2C interface you can use it with almost any development board like an Arduino, MicroPython or CircuitPython board.  This guide shows how to use the MPR121 capacitive touch sensing breakout with a CircuitPython board.

Before you follow this guide it will help to familiarize yourself with the following other guides:

Continue on to learn about the hardware needed to follow this guide.

This guide was first published on Mar 17, 2017. It was last updated on Jun 16, 2024.

This page (Overview) was last updated on Mar 08, 2024.

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