Capacitive Touch Sensor Controller - MPR121QR2

The MPR121QR2 is an I2C driven capacitive touch sensor controller, capable of managing up to twelve electrodes. The chip also has eight LED driving pins, which, when not configured to control electrodes, can be used to drive LEDs. The device also features a 13th simulated electrode that represents the simultaneous charging of all the electrodes connected together to allow for increased proximity detection in a touch panel or touch screen array.

The MPR121QR2 can operate at anywhere from 1.71 to 3.6VDC. It’s an Inter-Integrated Circuit (I2C) compliant device with an additional interrupt that is triggered any time a touch or release of a button is detected. The I2C address is also configurable via the ADDR pin.

It’s a tiny chip, with a 0.4mm pitch and a 3x3mm footprint. Look for a breakout board coming soon!

  • 1.71 V to 3.6 V operation
  • 29 μA supply current at 16 ms sample period
  • 3 μA shutdown current
  • 12 electrodes
  • Continuous independent auto-calibration for each electrode input
  • Separate touch and release trip thresholds for each electrode, providing hysteresis and electrode independence
  • LED driver functionality with 8 shared LEDs
  • I2C interface, with IRQ output to advise electrode status changes
  • 3 mm x 3 mm x 0.65 mm 20 lead QFN package
  • -40°C to +85°C operating temperature range

Capacitive Touch Sensor Controller - MPR121QR2 Product Help and Resources

MPR121 Hookup Guide

December 18, 2013

How to get started using the MPR121 for capacitive touch sensing with your Arduino.

Core Skill: Soldering

This skill defines how difficult the soldering is on a particular product. It might be a couple simple solder joints, or require special reflow tools.

3 Soldering

Skill Level: Competent - You will encounter surface mount components and basic SMD soldering techniques are required.
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Core Skill: Programming

If a board needs code or communicates somehow, you're going to need to know how to program or interface with it. The programming skill is all about communication and code.

3 Programming

Skill Level: Competent - The toolchain for programming is a bit more complex and will examples may not be explicitly provided for you. You will be required to have a fundamental knowledge of programming and be required to provide your own code. You may need to modify existing libraries or code to work with your specific hardware. Sensor and hardware interfaces will be SPI or I2C.
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Core Skill: Electrical Prototyping

If it requires power, you need to know how much, what all the pins do, and how to hook it up. You may need to reference datasheets, schematics, and know the ins and outs of electronics.

3 Electrical Prototyping

Skill Level: Competent - You will be required to reference a datasheet or schematic to know how to use a component. Your knowledge of a datasheet will only require basic features like power requirements, pinouts, or communications type. Also, you may need a power supply that?s greater than 12V or more than 1A worth of current.
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