MPR121

The MPR121 is a capacitive touch sensor controller that uses an I2C interface for control. The microprocessor can control up to twelve different electrodes, as well as a simulated thirteenth electrode. In addition, the MPR121 includes eight LED driving… pins, which are used to power LEDs that aren’t set as electrodes. There occurs four jumpers on the bottom base of the board, all of which are set (closed) by default.

Because an address jumper connects the ADD pin to ground, the chip’s default I2C address is 0x5A. If you need to change the chip’s address, make sure you open the jumper first (by shorting ADD to a different pin). Jumpers are used to link SDA, SCL, and the interrupt pin to 10k pull-up resistors. Cut the wire connecting the pull-up resistors and the jumpers if you don’t require them.

The MPR121 comes as the second-generation sensor controller after the release of the MPR03x series devices. The MPR121 features:

• A second-generation capacitance detecting engine has been added, as well as better internal intelligence.
• Increased electrode count, expanded filtering system with denouncing, and hardware configurable I2C address Completely separate electrodes with built-in auto-configuration are also offered.
• The simultaneous charging of all the electrodes is started by a 13th simulated electrode. In a touch panel or touch screen array, and joined together to enable for improved proximity detection: