I/O Port Expanders Tutorial
![I/O port expander](/images/IO-port-expander.png)
MCP230xx
How to Read Input from an MCP230xx I/O Port Expander Connected to an Arduino Microcontroller
MCP23008
How to Connect an MCP23008 I/O Port Expander to an Arduino Microcontroller
MCP23017
How to Connect an MCP23017 I/O Port Expander to an Arduino Microcontroller