Adafruit feather main boards adafruit 2829 the adafruit feather 32u4 bluefruit le board makes it easy to include bluetooth low energy ble in your next project ble is simple to use as its unencumbered by licensing and certification and its supported by all modern smartphones at its simplest you can use it as a serial data pipeline without worrying about protocols etc what goes in one end comes out of the other the atmel 32u4 is the big brother of the mcu thats been providing the ardu