The R2A20150NP/SA is a CMOS 8-bit I/O expander, which has serial to parallel and parallel to serial data converting functions. It can communicate with a microcontroller via few wiring thanks to the adoption of the 2-wire I²C BUS. Maximum 8 ICs can be connected to a bus by using 3-chip select pins, so that it is possible to handle up to 64 bits data.