The Raspduino is an Arduino compatible microcontroller board, designed to plug on top of a Raspberry Pi (some people like to call this a Pi Plate). It is then possible to add Arduino shields to the Raspduino.
The Raspduino is powered by a ATmega328 microcontroller, and can be programmed with the regular Arduino software. The Raspduino can communicate with the Raspberry Pi via the serial port or I2C port on the GPIO connector. Programming can also be done over the GPIO connector.
Documentation for the Raspduino
1 Raspduino V1.1
2 18mm metal spacer
4 M3 bolt