MCP23008 - i2c 8 input/output port expander

The MCP23008 is an I2C 8-bit I/O port expander that adds 8 general-purpose pins to your microcontroller using just two I2C lines (shared with other I2C devices). Each pin can be configured as input, output, or input with internal pull-up, and an external interrupt output notifies you when any input changes — no polling required.

Operating from 2.7–5.5 V, the chip works with both 3.3 V and 5 V systems. Each I/O pin can sink or source up to 20 mA, making it suitable for driving LEDs directly. The DIP-18 package plugs straight into a breadboard or perfboard.

Key Features

• 8 Configurable I/O Pins – Input, output, or input with pull-up on each pin
• I2C Interface – Uses only 2 bus lines, sharable with other I2C devices
• 3 Address Pins – Up to 8 devices on a single I2C bus (64 I/O pins total)
• Interrupt Output – External pin signals input changes without polling
• 20 mA Per Pin – Drive LEDs directly from the expander
• Wide Voltage Range – 2.7–5.5 V operation
• DIP-18 Package – Breadboard and perfboard friendly

Ideal For

• Expanding GPIO on Arduino, Raspberry Pi, or other microcontrollers
• Driving multiple LEDs or reading multiple buttons
• Projects requiring more I/O than the microcontroller provides

Resources

• Arduino Library (GitHub)