![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 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](https://m.media-amazon.com/images/I/81LF5fUXHLL.jpg)
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
![gpio - rPi model B + MCP23017 + relay board. GPA0 pin low output not close enough to 0v to trigger relay - Raspberry Pi Stack Exchange gpio - rPi model B + MCP23017 + relay board. GPA0 pin low output not close enough to 0v to trigger relay - Raspberry Pi Stack Exchange](https://i.stack.imgur.com/AFQYU.jpg)
gpio - rPi model B + MCP23017 + relay board. GPA0 pin low output not close enough to 0v to trigger relay - Raspberry Pi Stack Exchange
![MCP230xx IO Expander | Character LCD with Raspberry Pi or BeagleBone Black | Adafruit Learning System MCP230xx IO Expander | Character LCD with Raspberry Pi or BeagleBone Black | Adafruit Learning System](https://cdn-learn.adafruit.com/assets/assets/000/018/263/medium800/raspberry_pi_RaspberryPiRGB_MCP_bb.png?1405985057)