All wiring diagrams to be place in here.

MCP23017 port expander

An example of wiring a single MCP23017 to add 16 additional GPIO pins. This example is wired to give the MCP23017 a device ID of 0.

MCP23S17 port expander

An example of wiring a single MCP23S17 to add 16 addition GPIO pins. This example is wired so that the MCP23S17 operates on SPI port 0 with a device ID of 0.

MCP23S17 Chaining

An example of wiring multiple MCP23S17 to add 32 addition GPIO pins. This example is wired so that 2 MCP23S17's operate on SPI port 0 with a device ID of 0 for the first chip and a device ID of 7 for the second chip

NOTE: It is possible to chain 8 MCP23S17's together for a total of 128 GPIO pins per SPI Select. Since the RaspberryPi has 2 SPI Selects you can theoretically use 16 MCP23S17's for a total of 256 channels.

Raspberry Pi P1 Header

Credits: wiringpi.com

Raspberry Pi P5 header (r 2.0)