The little chip in the middle of the PCB is the actual MPR121 sensor that does all the capacitive sensing and filtering. We add all the extra components you need to get started, and you can connect to this board using STEMMA QT / QWIIC connectors. There are a series of 12 chonkpads for touch sensing with your finger or for easily connecting up alligator/croc clips.

STEMMA QT Connector Pins

The STEMMA QT connectors allow you to connectors to dev boards with STEMMA QT connectors or to other things with various associated accessories.

The sensor on the breakout requires 3V power. Since many customers have 5V microcontrollers like Arduino, we tossed a 3.3V regulator on the board. Its ultra-low dropout so you can power it from 3.3V-5V just fine.

• Vin - this is the power pin. Since the chip uses 3 VDC, we have included a voltage regulator on board that will take 3-5VDC and safely convert it down. To power the board, give it the same power as the logic level of your microcontroller - e.g. for a 5V micro like Arduino, use 5V
• GND - common ground for power and logic
• SCL - I2C clock pin, connect to your microcontrollers I2C clock line. Can use 3V or 5V logic, and has a 10K pullup.
• SDA - I2C data pin, connect to your microcontrollers I2C data line. Can use 3V or 5V logic, and has a 10K pullup.

Address Jumper

The default I2C address for this chip is 0x5A.

• addr - This jumper can be bridged to change the I2C address to 0x5B.