MCP23S17 with 2 X ULN2803 SPI serial I/O extension board expander Arduino Raspberry

This extension board is designed to have 16 output ports over the SPI protocol on two ULN2803 Darlington arrays. It uses an MCP23S17 SPI controller to drive both ULN2803 Darlington arrays to switch relays, LEDs, etc. With the DIP switch, You can choose the SPI address, if You need to have two or more board connectors on the same device.