From “The Pololu m3pi robot consists of a 3pi robot base with a fully assembled m3pi expansion board as its second level. This expansion board enables the use of a powerful 32-bit mbed development board as the robot’s high-level controller, which offers significantly more processing power and free I/O lines than the 3pi’s built-in 8-bit AVR microcontroller. There are also sockets for Wixel and XBee wireless serial modules as well as prototyping space for additional sensors and electronics.”