The Romi 32U4 Control Board has several expansion areas (primarily in three groups near the front left and middle and back right edges) that break out all of the general-purpose I/O lines from the ATmega32U4 microcontroller and the Raspberry Pi. The board also provides access to various power inputs, outputs, and control pins, and it makes a few stand-alone buses available to help you make connections. The following diagrams identify the locations of these pins and the hardware associated with them; they are also available as une [https://www.pololu.com/file/0J1261/romi-32u4-control-board-pinout-power.pdf version PDF imprimable] (1Mio pdf). For more information about the ATmega32U4 microcontroller and its peripherals, see Atmel’s ATmega32U4 documentation.