The MCP23008 I²C DIO8 device provides an 8-bit general purpose, parallel I/O expansion for the I²C bus.
This device contains 3 address pins and multiple configuration registers for input, output, and polarity selections.
The system master has the ability to enable the GPIO port as either inputs or outputs by programming the configuration bits.
Up to 8 MCP23008 chips may be chained to each I²C port using 3 on-board address jumpers.
Do not exceed 5VDC on any input. May be powered by the I²C bus or powered externally (jumper-selectable).