The Proximity Plug is a small board which uses the MPR084 to support up to 8 capacitive input ("touch") switches. A solder jumper allows using up to two of these plugs on a single port. The chip can be configured to allow only single touch or multiple switch contacts at the same time, and will do an auto-calibration to adjust for differences between the sensor surfaces.
An I2C bus running at 3.3V is used for I/O, with all the power and signal lines brought out to to both sides of the board to allow daisy-chaining with other I2C-conformant boards.
For additional details, see http://jeelabs.org/2010/10/25/meet-the-proximity-plug/
There is one solder jumper to configure each plug for one of the following 7-bit I2C addresses:
Dimensions: 21.1 x 24.1 mm
CadSoft EAGLE design files: see below.
This board uses the conventions of a JeePlug and can be used with the ports on a JeeNode. It can also be used with other boards and MCU's, if you hook it up properly and adapt the interface code for it.