This add-on board for the Raspberry Pi puts at your disposal 4 motor-control outputs for powerful LEGO EV3 Mindstorms motors and 16 buffered I/O connections. The HAT (hardware attached on top) is complying with a specific set of rules. When connected to the PI, it is automatically recognized: GPIOs and drivers for the board are configured consequently, making life easier!
Built-in optical encoders generate pulses when a motor rotates. This feedback signal can be used to measure the speed and position of the motor’s axis, allowing control within one degree of accuracy.
All kinds of sensors and actuators –not only LEGO- can be connected to the RPi’s I2C bus via two MCP23008 I/O-expanders. The Raspberry Pi can add keyboard, mouse, camera, WiFi, Bluetooth, Ethernet, display etc. to your design, and of course more RPi modules can be combined to allow more complex control in your LEGO projects.
Programming is possible in languages such as C and Python.
 

Elektor LABS: Raspberry Pi goes LEGO!   |   Elektor SHOP:  LEGO RPI BOARD (159010-91)