Product description: GPIO expander and Keypad Matrix controller - for matrix keyboards - TCA8418 - STEMMA QT / Qwiic - Adafruit 4918
The Adafruit module is equipped with the TCA8418 chip working as a matrix keyboard controller. The chip has a total of 18 I / O pins in a 10 column and 8 row arrangement that can be arranged as a matrix of buttons on a total of 80 switches, or you can use any subset as an individual GPIO input or output. The controller has 10 bytes of FIFO to store the 10-element event queue. The Adafruit 4918 module can also be used as a standard GPIO pin expander , which extends the design possibilities by 18 ports.
The manufacturer has also prepared a detailed user guide - check it out!
Elements included in the kit.
All pins on the board have markings, which greatly facilitates prototyping.
Pinout description
- VIN - power pin from 3 V to 5 V DC
- 3Vo - 3.3V output from the voltage regulator
- GND - the ground of the system
- SCL - clock line of the I2C bus
- SDA - data line of the I2C bus
- C0 - C9 - GPIO pins or columns in the keyboard matrix. The column number corresponds to the pin number
- R0 - R7 - GPIO pins or rows in the keyboard matrix. The row number corresponds to the pin number
- INT - Open-drain - active-low interrupt output
- RST - reset pin
Technical Specifications
- Built-in chip: TCA8418
- Standby (idle) current consumption: 3 μA
- Supports 80 buttons using 18 GPIO pins
- Supports QWERTY keyboards and GPIO extensions
- Supports 1-MHz Fast Mode Plus I2C bus
- Storage memory: 10 bytes of FIFO
- Communication interface: I2C bus
- Interface address: 0x34 (default)
- Conclusions:
- solder pads (goldpin 2.54 mm strip is included in the set)
- STEMMA QT / Qwiic connectors
- Tile sizes: 35.5 x 17.7 x 4.6 mm
Kit contents
- GPIO expander and Keypad Matrix controller - for matrix keyboards - TCA8418 - STEMMA QT / Qwiic - Adafruit - 1 piece
- 1x16 goldpin strip - 2.54 mm raster - 2 pieces
An example of a connection diagram using Adafruit 4918.
