Using the MCP23017 port expander with WiringPi2 to give you 16 new GPIO ports – part 3 – RasPi.TV
Amazon.com: CQRobot Ocean: MCP23017 IO Expansion Board Compatible with Raspberry Pi/Micro:bit/Arduino/STM32 Motherboard. I2C Interface, Expands 16 I/O Pins, Up to 8 Expansion Boards Can be Used Simultaneously. : Electronics