Adafruit TCA8418 Keypad Matrix and GPIO Expander Breakout

It's a GPIO expander, it's a keypad matrix driver... its the Adafruit TCA8418 Keypad Matrix and GPIO Expander Breakout - a cute and powerful I2C GPIO expander and keypad matrix driver! This chip is quite fancy, with the ability to act as your I2C multi-tool for handling keypads,…

VIN
Board power input. Adafruit says to power it from the same voltage as the microcontroller logic level.
Type · powerVoltage · 3V to 5V input, regulated down for the 3V TCA8418 chip, per Adafruit Learn.
3Vo
3.3V output from the onboard regulator.
Type · power outputVoltage · 3.3V output, up to 100mA per Adafruit Learn.
GND
Common ground for power and logic.
Type · groundVoltage · 0V
SCL
I2C clock line to the host microcontroller, level shifted, with 10k pull-up.
Type · i2cVoltage · 3V to 5V logic supported per Adafruit Learn.
SDA
I2C data line to the host microcontroller, level shifted, with 10k pull-up.
Type · i2cVoltage · 3V to 5V logic supported per Adafruit Learn.

Start wiring

I2C · SPI · 3V to 5V input, regulated down for the 3V TCA8418 chip, per Adafruit Learn. · 3.3V output, up to 100mA per Adafruit Learn.

Confirm the data interface matches your host board.

Module pins: VIN, GND, SCL, SDA, C0-C9, R0-R7. Schematik maps them to your board in the app.

Related groups

4 groups

Displays

Character LCDs, SPI TFTs, e-paper modules and larger capacitive-touch TFT panels solve different display jobs. Treat display class, interface, controller, resolution, touch, refresh behaviour, storage, voltage and mounting as separate swap checks.

Displays · TFT & LCD displays · 35 parts

Connectors

Sort passive connector adapters from Qwiic boards, LCD modules and microSD card adapters before assuming anything with the right plug will substitute safely.

Connectors & cables · Connectors · 28 parts

Air quality

Choose between MQ gas sensors, VOC/eCO2 indoor-air sensors, true CO2 modules and particulate sensors without treating every air-quality breakout as the same detector.

Sensors · Gas & air-quality sensors · 31 parts

MCUs and boards

ESP32, Arduino Uno, Raspberry Pi Pico, and compatible add-on boards for running builds.

Boards · Microcontroller boards · 24 parts

Pin	Type	Function	Voltage
VIN	power	Board power input. Adafruit says to power it from the same voltage as the microcontroller logic level.	3V to 5V input, regulated down for the 3V TCA8418 chip, per Adafruit Learn.
3Vo	power output	3.3V output from the onboard regulator.	3.3V output, up to 100mA per Adafruit Learn.
GND	ground	Common ground for power and logic.	0V
SCL	i2c	I2C clock line to the host microcontroller, level shifted, with 10k pull-up.	3V to 5V logic supported per Adafruit Learn.
SDA	i2c	I2C data line to the host microcontroller, level shifted, with 10k pull-up.	3V to 5V logic supported per Adafruit Learn.
STEMMA QT	connector	STEMMA QT/Qwiic I2C connector for compatible boards and accessories.	I2C connector follows board power/logic level.
C0-C9	gpio	GPIO or keypad matrix column pins. Column number corresponds with pin number.
R0-R7	gpio	GPIO or keypad matrix row pins. Row number corresponds with pin number.
INT	interrupt	Open-drain active-low interrupt output.
RST	reset	Active-low reset input.
Power LED	indicator	Green onboard power LED labelled on.

Pinout

Start wiring

Displays

Connectors

Air quality

MCUs and boards