https://devzone.nordicsemi.com/f/nordic-q-a/6238/nrf51422-usb-dongle---p0-30-functionHello. I am looking at the schematic of the nRF51422 USB dongle development kit. The pin P0.30 of the microcontroller is attached to ground. As the pin could potentially have multiple functions (depends on what function you program on this pin), Ien-USTelligent Community 13Thu, 26 Mar 2015 14:15:48 GMThttps://devzone.nordicsemi.com/thread/21846?ContentTypeID=1Thu, 26 Mar 2015 14:15:48 GMT137ad170-7792-4731-bb38-c0d22fbe4515:a94343f0-de7c-43b5-9443-dda6c131802cHung Bui<p>Hi Otxoasound,</p> <p>The pin is connected to ground because we have an earlier version of the dongle that use different GPIO pin for UART. And to distinguish between the first version and the current version we connect pin 30 to ground on current version, so that the dongle firmware can automatically configure the pin to match with the hardware version.</p><div style="clear:both;"></div>