The Pi Co-op is an Arduino compatible microcontroller expansion board for the Raspberry Pi. The Pi Co-op makes it much easier to hook up electronics to the Raspberry Pi than using the GPIO pins directly, and provides a powerful programmable microcontroller that can take care of your low level hardware whilst the Pi focuses on the higher level computation.

The Pi Co-op brings the worlds of the Raspberry Pi and the Arduino together, and means that you don't have to make the false choice between an Arduino or a Pi for your next project. Use the best bits of both! 

Model B+ Compatibility: We've tested the Pi Co-op with the new Model B+ and it works great. The only slight problem is that the Pi Co-op covers over the new position of the camera connector on the Model B+. This means that you need to bend the camera cable to fit it into the camera connector and you might need to get a longer camera cable to get it to go where you want, compared with the cable you'd need for the Model A or Model B.

Updated: The Pi Co-op is now supplied with extended GPIO headers so you can use GPIO pins not used by the Pi Co-op for your own projects.

Features 

• Atmega328p microcontroller preprogrammed with the Arduino Uno bootloader.
• 10bit 8 channel Analog to Digital Converter (ADC).
• Can be programmed directly from the Raspberry Pi using the free Arduino IDE.
• Level shifted UART for fast communication between the Pi and Pi Co-op at a baud rate of up to 115200bps.
• Atmega328p pins broken out to female headers for easy prototyping, just plug in wires or connect to a breadboard.
• Power line incorporates the same type of fuse used on the Pi MicroUSB connector (700mA hold current, 1100mA trip current). This allows the Pi to be safely powered from an external 5V supply attached to the Pi Co-op.
• Standard spacing of 2.54mm between all headers allows expansion boards to be created easily using copper stripboards.
• Extended GPIO header pins

Useful Links

Manual

Software needed to set up Pi Co-op on a Raspberry Pi (please see the Manual for details)

Tutorial showing how to use the Pi Co-op as a general purpose I/O board for the Raspberry Pi, and controlling it with Python, Javascript etc

Schematic for the Pi Co-op