MPR121 Capacitive Touch Sensor Breakout
The MPR121 is a microchip that can evaluate up to 12 capacitive electrodes. The breakout board is connected to your Arduino via the I2C bus. Thanks to the I2C, there is no need for elaborate wiring and the control is very easy to implement with the appropriate library. The MPR-121 can be addressed via the address pin. This means you can operate up to MPR121 breakout boards on one I2C bus. Thus, you could read and evaluate 4×12 48 electrodes. As electrodes, you can use conductive materials or even organic ones that are slightly conductive. For example, fruits and vegetables :-). I often also use copper adhesive tape. You can, for example, stick this on the back of a piece of paper and when you then touch the paper on the other side, this touch can be evaluated.
You can find a suitable library on GitHub at the following link:
.BareConductive/mpr121
Downloads:
- MPR121_Datasheet.pdf
Connections on the MPR121:
| MPR121 Breakout | Arduino UNO |
| 3.3V | 3.3V |
| IRQ (Interrupt) | 4 |
| SCL | A5 |
| SDA | A4 |
| GND | GND |
Addressing the MPR121:
For the addressing to work, you first have to cut the «ADD» bridge on the back with a hobby knife.
| ADD Pin on MPR121 | I2C address |
| Not connected | 0x5A |
| Connected with 3V | 0x5B |
| Connected with SDA | 0x5C |
| Connected with SCL | 0x5D |
Technical Details:
- Operating voltage: 3.3V
- I2C Logic Voltage: 3.3V or 5V
- Channels: 12
- Default I2C Address: 0x5A
- Measuring range: 054612 Lux
- Grid dimension: RM 2.54mm
- Size: 30 x 20 x 2mm
- Total Weight: 3g
Delivery Contents:
- 1x MPR121 Capacitive Touch Sensor
- 1x Pin Header (6 Pin)
- 1x Pin Header (12 Pin)
