I/O Expander - MCP23008

The Sparkfun MCP23008 port expander is a powerful tool that allows you to add an additional eight pins to your microcontroller. It utilizes two I²C pins, which can be shared with other I²C devices, providing eight general-purpose pins in return. Each of these pins can be set as input, output, or input with a pullup. An added feature is the ability to receive an interrupt through an external pin when any of the inputs change, eliminating the need to constantly poll the chip.

The MCP23008 port expander operates between 2.7-5.5V, making it suitable for any 3.3V or 5V setup. It can sink/source up to 20mA from any of the I/O pins, making it perfect for LEDs and similar devices. If you require more power, simply pair it with a high-power MOSFET. Its DIP package design allows it to plug into any breadboard or perfboard.

With the MCP23008, you have the ability to set the I²C address by tying the ADDR0-2 pins to power or ground. This allows up to eight unique addresses, meaning eight chips can share a single I²C bus, providing 64 I/O pins!

Key Features:

• 8-bit remote bidirectional I/O port
• High-speed I²C interface (MCP23008)
• Hardware address pins
• Configurable interrupt output pin
• Configurable interrupt source
• Polarity Inversion register for input port data polarity configuration
• External reset input
• Low standby current: 1 µA (max)
• Operating voltage ranges suitable for various temperature conditions

This port expander is a versatile and efficient solution for those looking to increase the functionality of their microcontroller. Whether you're working on a small home project or a larger, more complex system, the MCP23008 offers a reliable and easy-to-use solution.

Additional Resources:

• Datasheet
• Bourns EAW - ACE GitHub