Adafruit TCA8418 Keypad Matrix and GPIO Expander Breakout - STEMMA QT / Qwiic

The Adafruit TCA8418 Keypad Matrix and GPIO Expander Breakout is a versatile I2C GPIO expander and keypad matrix driver that packs a lot of power into a small package. With 18 total I/O pins, including 10 columns and 8 rows, this chip is perfect for handling keypads, buttons, or LEDs in your projects. You can use it to create a keypad matrix with up to 80 switches, or configure the pins as individual GPIO inputs or outputs.

Key Features:

• GPIO Expansion: The 18 I/O pins can be individually configured as inputs or outputs. You can set optional pull-ups for inputs and use the interrupt output for rising or falling signals. It also includes a debouncer to filter noise from tactile switches.
• Keypad Matrix Driver: Supports up to 10 columns and 8 rows for a keypad matrix. It manages the pull-ups and scanning automatically and stores keypress/release events in a 10-element FIFO queue. Interrupt output is available for key press or release, eliminating the need for constant polling.
• I2C Communication: Easily connect to any microcontroller or computer via I2C. It uses only two I2C pins and can be shared with other devices or sensors. You can even add more expanders for expanded I/O control.
• 3.3V or 5V Compatibility: Built-in 3.3V regulator and level shifting on I2C lines allow you to use this with 3V or 5V microcontrollers.
• STEMMA QT Form Factor: The breakout features STEMMA QT connectors for easy, solderless connections to your development board. It's compatible with SparkFun Qwiic I2C connectors, so you can easily chain it with other compatible sensors and accessories.
• Libraries and Drivers: Adafruit provides both Arduino and CircuitPython/Python libraries for easy integration. There's also a Linux Kernel driver module for native support on single-board computers like Raspberry Pi.

This breakout is ideal for projects that need additional GPIO or keypad functionality without requiring a microcontroller with a massive number of I/O pins. It’s quick to set up, easy to use, and gives you the flexibility to expand your project's input/output capabilities over I2C.

The TCA8418 Keypad Matrix and GPIO Expander is a compact, low-power solution for managing keypads, buttons, or LEDs via I2C. Here are the key technical details:

• Supports 80 Buttons: Uses 18 GPIOs to support up to 80 buttons, ideal for keypad matrix or GPIO expansion.
• QWERTY Keypad & GPIO Expansion: Perfect for creating QWERTY keypads or adding extra GPIOs to your project.
• Low Standby Current: Only 3 μA (excluding breakout board regulator and LED), making it highly energy-efficient.
• Fast I2C Communication: Operates on a 1-MHz Fast Mode Plus I2C bus for quick data transfer.
• 10-Byte FIFO Queue: Stores up to 10 key presses and releases for efficient event handling.
• Interrupt Output: Features an open-drain, active-low interrupt output to signal keypress/release events.
• Integrated Debouncing: Includes a built-in debounce time of 50 μs to filter noise from switches.
• Dimensions: 35.5mm x 17.7mm x 4.6mm (1.4" x 0.7" x 0.2").
• Weight: 2.5g (0.1oz).

Note: The JST connector may be off-white or black, depending on availability.