I/O Expansion Board for Raspberry Pi - 

Gertboard is an input/output (I/O) extension board for the Raspberry Pi computer. It fits onto the GPIO pins of the Raspberry Pi (the double row of pins on the upper left corner) via a socket on the back of the Gertboard. A bit of care is required when putting the two devices together. It is easy to insert just one row of pins into the socket, but all of the pins need to be connected. The Gertboard gets its power from those GPIO pins, so user will need a power supply for the Raspberry Pi (RPi) that is capable of supplying a current of at least 1A. It is a flexible experimenter board that plugs directly into Raspberry Pi, and out into the physical world, allowing user to detect and respond to external physical events. Detect and output analogue voltages. Drive powerful motors. Detect switch presses. Illuminate LEDs and drive relays. Jumper cables allow user to hook up different parts of the circuit in many different ways, allowing total flexibility. All controlled by Raspberry Pi.