Adafruit bi colour redgreen led displays with i2c backpack kit adafruit 902 these adafruit square bi colour redgreen led 12in 8x8 matrix displays with i2c save your microcontroller losing all its gpios to multiplexing connecting displays like this can be quite expensive in precious gpio pins but with the added backpack they only use the 2 x i2c signals plus 2 x power connections they are great for microcontrollers with limited outputs such as the adafruit trinkets which only have 5 x