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MPR121 Proximity Capacitive Touch Sensor Development Board

Reference: MD0118

Condition: New product

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Detail about MPR121 Proximity Capacitive Touch Sensor Development Board

Description

This is a breakout board for Freescale's MPR121QR2. The MPR121 is a capacitive touch sensor controller driven by an I2C interface. The chip can control up to twelve individual electrodes, as well as a simulated thirteenth electrode. The MPR121 also features eight LED driving pins. When these pins are not configured as electrodes, they may be used to drive LEDs.
There a four jumpers on the bottom of the board, all of which are set (closed) by default. An address jumper ties the ADD pin to ground, meaning the default I2C address of the chip will be 0x5A. If you need to change the address of the chip (by shorting ADD to a different pin), make sure you open the jumper first. Jumpers also connect SDA, SCL and the interrupt pin to 10k pull-up resistors. If you don't require the pull-up resistors you can open the jumpers by cutting the trace connecting them.
There is no regulation on the board, so the voltage supplied should be between 2.5 and 3.6VDC. The VREG pin is connected through a 0.1uF capacitor to ground, which means, unless you modify the board, you can't operate the MPR121 in low-supply voltage mode (1.71-2.75VDC).

The MPR121QR2 is a capacitive touch sensor controller that makes it very easy to integrate capacitive touch sensing into your project. It communicates via I2C, and works by measuring the capacitance of twelve electrode points. When an object comes close to the electrode connector, the measured capacitance changes. This signals the MPR121 that something has touched a ‘button’. The IC is also capable of driving LEDs or basic GPIO functionality on electrode pins 4 through 11, giving you a lot of freedom for setting up your project. The sensor works from 1.6V to 3.3V. The sensor isn’t very current-hungry, drawing only around 29 µA when sampling every 16 milliseconds.

Features

Uses I2C 7-bit address 0x5A (can be set to 0x5B, 0x5C or 0x5D)
Low power operation
1.71 V to 3.6 V supply operation
29 μA supply current at 16 ms sampling interval period • 3 μA Stop mode current
 12 capacitance sensing inputs
8 inputs are multifunctional for LED driver and GPIO
 Complete touch detection
Auto-configuration for each sensing input • Auto-calibration for each sensing input
Touch/release threshold and debounce for touch detection
 I2C interface, with Interrupt output
 3 mm x 3 mm x 0.65 mm 20 lead QFN package
 -40°C to +85°C operating temperature range