Adafruit 056 4 digit 7 segment displays with i2c backpack adafruit 881 these adafruit blue 4 digit 7 segment displays take the pain out of using 7 segment displays by including an i2c backpack to do the constant current driving and 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 trink