Adafruit featherwing add ons for all feather boards adafruit 2922 the adafruit adalogger featherwing add ons combine a real time clock rtc a battery backup and an sd card interface so that you can get on with some time stamping data logging they are compatible with all the feather main boards and are controlled via i2c with an spi channel to the sd card adafruit supply a library for the real time clock which you are free to download and the default arduino sd library will handle the sd c