The MPR121 has support for only I2C, which can be implemented with nearly any microcontroller. You can select one of 4 addresses with the ADDR pin, for a total of 48 capacitive touch pads on one I2C 2-wire bus. Using this chip is a lot easier than doing the capacitive sensing with analog inputs: it handles all the filtering for you and can be configured for more/less sensitivity.
This sensor comes as a tiny hard-to-solder chip so we put it onto a breakout board for you. Since it's a 3V-only chip, we added a 3V regulator and I2C level shifting so its safe to use with any 3V or 5V microcontroller/processor like Arduino. We even added an LED onto the IRQ line so it will blink when touches are detected, making debugging by sight a bit easier on you. Comes with a fully assembled board, and a stick of 0.1" header so you can plug it into a breadboard. For contacts, we suggest using copper foil or pyralux, then solder a wire that connects from the foil pad to the breakout.
Getting started is a breeze with our Arduino library and tutorial. You'll be up and running in a few minutes, and if you are using another microcontroller, its easy to port our code.
Of course, we wouldn't leave you with a datasheet and a "good luck!" - we wrote a detailed tutorial showing how to wire up the sensor, use it with an Arduino and example code that gets the sensor logging data and detecting your touch!
- Dimensions: 33mm x 19mm x 2mm / 1.3" x .8" x .1"
- Weight: 2.2g
- Uses I2C 7-bit address 0x5A (can be set to 0x5B, 0x5C or 0x5C)
- MPR121 Datasheet
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This depends on where you are located. After the order is handed over to UPS, the delivery time in Germany is about 2-3 days, within Europe about 1 week.
We ship our orders with UPS (United Parcel Service).