MPR121 Capacitive Touch Sensor Breakout

The MPR121 evaluates up to 12 capacitive electrodes and is connected via I2C. Four addresses can be set using the ADD pin, so up to four breakout boards with a total of 48 electrodes can run on one I2C bus. Suitable electrodes are conductive materials such as copper tape, which can also be stuck to the back of paper, or slightly conductive organic things such as fruit and vegetables.

Recommended alternative for a single button: Capacitive Touch Sensor Button TTP223

Recommended Accessories:

• 20mm Copper Adhesive Tape 10m
• Logic Level Converter 2-Channel 5V / 3.3V
• Dupont Cable M-F 20cm 20 Pieces

Features:

• 12 electrodes, pins 0 to 11
• IRQ signals changes, the touch state is read via I2C
• No voltage regulator and no level shifter can be seen on the board: supply with 3.3 V, a level shifter is recommended for SDA and SCL on 5 V boards
• To change the address, first cut the ADD solder bridge on the back

Application Examples:

• Touch keypads and control panels
• Invisible buttons behind paper
• Interactive objects with fruit, vegetables or copper tape

Documentation:

• MPR121 tutorial (Adafruit, same chip, different board with regulator)
• Adafruit MPR121 library (GitHub)
• Bare Conductive MPR121 library (GitHub)
• MPR121 datasheet (PDF)

Technical Data:

• Chip: MPR121
• Operating voltage: 3.3 V (chip per datasheet 1.71 to 3.6 V)
• Channels: 12
• Interface: I2C
• Pins: 3.3V, IRQ, SCL, SDA, ADD, GND, electrodes 0 to 11
• I2C address: ADD to GND (factory setting via the solder bridge) 0x5A, to 3.3 V 0x5B, to SDA 0x5C, to SCL 0x5D
• Pin pitch: 2.54 mm
• Size: 30 × 20 × 2 mm
• Weight: 3 g

Scope of Delivery:

• 1× MPR121 capacitive touch sensor
• 1× Pin header (6-pin)
• 1× Pin header (12-pin)