The Adafruit TCA8418 Keypad Matrix and GPIO Expander Breakout is a versatile I2C GPIO expander and keypad matrix driver. With 18 I/O pins (10 columns and 8 rows), it can manage up to 80 switches in a matrix configuration or serve as individual GPIO inputs and outputs.

Whether you need more buttons, LEDs, or a full keypad matrix for your project, this breakout handles it all over a simple I2C connection. It features a 10-element event queue so key presses and releases are stored even if you can't respond to the interrupt immediately. The built-in STEMMA QT connectors and onboard 3.3V regulator with level shifting make it compatible with both 3V and 5V microcontrollers.

Key Features

• 18 I/O Pins – 10 columns and 8 rows, configurable as a keypad matrix (up to 80 switches) or individual GPIO
• 10-Element FIFO Event Queue – Stores key press and release events so you never miss an input
• I2C Interface – Easy to connect and share the bus with other sensors and devices
• GPIO Inputs with Pull-ups – Optional pull-up resistors, interrupt output on INT pin for rising or falling signals, and built-in debouncer for noisy tactile switches
• GPIO Outputs – Set pins high or low for basic LED driving
• Interrupt Support – Configurable interrupt output on key press or release, no need for constant polling
• STEMMA QT / Qwiic Compatible – Solderless STEMMA QT connectors on both sides, compatible with SparkFun Qwiic
• Onboard Voltage Regulation – Built-in 3.3V regulator and I2C level shifting for 3V or 5V microcontrollers

Ideal For

• Custom keypads and button matrices
• Expanding GPIO on pin-limited microcontrollers
• LED control arrays
• Projects requiring interrupt-driven button input
• I2C sensor and peripheral chains

Package Contents

• 1× Adafruit TCA8418 Keypad Matrix and GPIO Expander Breakout

Resources

• Arduino Library (GitHub)
• CircuitPython / Python Library (GitHub)
• Linux Kernel Driver Module