CoPiino is a Raspberry Pi HAT that stacks perfectly on Raspberry Pi Models A/B/B+/2 and is equiped with an AVR microcontroller which behaves like Arduino.
CoPiino is designed to cooperate with Raspberry Pi and interfaces to your Arduino shields. This symbiosis combines the connectivity of the Pi and the realtime performance of the CoProcessor.
AVR ATmega @ 16MHz, 128kb flash, 16kb ram, 4k eeprom