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

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!