The MPR121 capacitive keypad uses the MPR121 and 12 touch sensitive pads to give you a simple 'keypad' with an I2C output. The board also has four mounting holes allowing it to be used as an input system in place of traditional buttons.
The keypad has 5 lines that need to be connected to your microcontroller, including the power lines, the IRQ line and the I2C lines.
ConnectionsMPR121 Keypad → Arduino Uno
- 3.3V → 3.3V
- SCL → A5
- SDA → A4
- GND → GND
- IRQ → D2
Check out the Fritzing diagram below to verify your connections.
This diagram shows the bottom side of the keypad, in order to show you the location of the I2C address jumper. In this diagram, the jumper is set to 0, but if you need to have 2 keypads on the same I2C bus, you can change one of them to be set to 1.
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