If you run out of GPIOs on your board, the easy way is to add an I2C GPIO expander, but those are normally limited to 8 or 16-channels, so Land Boards decided to create a board with 8 IO expanders making it a 128 channel IO expander that works on Raspberry Pi, BeagleBone Black, Arduino, and basically any boards with an I2C hardware or software implementation.
- 8x Microchip MCP23017 16-bit I/O expander for up to 128 GPIOs
- Communication Interface – I2C host interface with 100/400 KHZ operation; 4-pin host interface connector (Ground, Power, Clock, Data)
- 8x 20-pin 2.54mm pitch connectors with 16 I/Os, 2x VCC, and 2 ground
- 2x 4-pin interrupt connectors
- Data Storage – Microchip 24LC024 2K EEPROM with board info.
- 3.3V or 5V operation
- Dimensions – 95 x 95 mm
You can find out to use the board in the Wiki for code for Raspberry Pi, and Arduino, Since it’s using address range 0x20-0x27 of the I2C, you could most probably use it for other boards such as ESP8266 module or STM8s boards for some extra efforts provided there’s enough storage and memory.