MCP23017 16-Bit I/O Expander

The Microchip MCP23017 is a versatile I/O expander that allows you to add 16 additional GPIO pins to your microcontroller using just two I2C wires (SDA and SCL). It features configurable internal pull-up resistors and interrupt outputs, meaning it can alert your main processor when a button is pressed, rather than requiring constant polling. This chip is the standard solution for expanding inputs on Arduino, ESP8266, and Raspberry Pi projects.