BB Black to Arduino expansion board, compatible with UNO (default) and Leonardo (configuration); Arduino port, convenient to connect Arduino compatible modules, such as Motor Control Board; ICSP port, Arduino program download port, BB Back DEBUG port; With power indicator light; VIN voltage jumper selection, VDD 5V / self-defined voltage selectable; IOREF voltage jumper selection, SYS 5V / 3V3 selectable.