The MCP23S17 device family provides 16-bit, general purpose parallel I/O expansion for SPI applications.
The 16-bit I/O port functionally consists of two 8-bit ports (PORTA and PORTB).
- 16-bit input/output port expander with interrupt output
- Cascadable for up to 8 devices on one bus
- 25mA sink/source capability per I/O
- Three hardware address pins to allow up to eight
devices on the bus
- High-speed SPI interface (MCP23S17)
MCP23017/MCP23S17 Data Sheet
If you would like to convert your I2C LCD Interface into a SPI version, remove the included MCP23017 and replace it with the MCP23S17.
For more information about using the LCD Interface as an SPI version, check here I2C / SPI LCD Interface info.
The MCP23S17 is used also used in the Project 64 button board.