A quick Pibow mod to embed Adafruit’s Trellis nicely. Slight port of Adafruit’s Arduino code to show the lights working. The Green LEDs are far too dim. I know this. They were the ones I had to hand for testing 😉
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.