Tutorials & Projects

Adafruit Trellis Monochrome Driver PCB for 4x4 Keypad & 3mm LEDs /ADA1616

£10.50 £8.75 ex. VAT
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Trellis is an open source backlight keypad driver system. It is easy to use, works with any 3mm LEDs and eight tiles can be tiled together on a shared I2C bus. Each Trellis PCB has 4x4 pads and 4x4 matching spots for 3mm LEDs.

This item is just for the Trellis driver PCB assembly: LEDs and buttons not included.

You'll probably need the matching button pad, as well as some 3mm diffused LED's. Some soldering will is required for construction. The PCB doesn't contain a microcontroller so you'll also need an Arduino or similair to read the keypress data and let it know when to light up the LED's.

  • The circuitry on-board handles the background key-presses and LED lighting for the 4x4 tile.
  • Each tile has an I2C-controlled LED sequencer and keypad reader already on it.
  • The chip controls all 16 LEDs individually, turning them on or off (no grayscale or dimming) as well as reading any keypresses made with the rubber keypad.
  • The connections are 'diode multiplexed' so you do not have to worry about "ghosting" when pressing multiple keys, each key is uniquely addressed.
  • Each LED is multiplexed with a constant-current driver, so you can mix and match any colors you like. Any 3mm LED can be used, although we find that diffused LEDs with 250mcd+ brightness look best. 

Need more than 4x4 buttons? No problem, the tiles have 3 address jumpers and you can tile up to 8 PCB's together on a single I2C bus, as long as each one has a unique address. That's up to 128 LED's and buttons using only 2 I2C wires!

  • tiles connect by the edges with solder, and share the same power, ground, interrupt, and i2c clock/data pins.
  • connect the tiles in any configuration you want as long as each tile is connected to another with the 5 edge-fingers.

For more information, check out Adafruit's Arduino library and example code and their tutorial with wiring diagrams, installation instructions and example code!