by FHuettig » Wed Jul 09, 2014 3:12 pm
Those are the UART connections. When the board is booting you can monitor the process through those pins, if it does not boot you can do some debug and even reflash the board if needed, and once it boots you can use it as a terminal to access the board without any other peripherals or network connection. I've seen projects that use it to control external devices.
Be aware, though, that it is NOT an RS-232 compatible port as the signals are 0-3.3V rather than RS-232's bipolar standard of up to +/-15V. There are USB-UART adapters available that can connect directly to the unipolar signals on the Parallella.
-- Fred -- Hardware Guy --
