Virtual UART is a feature that allows a serial UART interface to be emulated over the debug connector ordinarily used for programming and SerialWire debugging. On the EFR32MG, it makes use of SerialWire's SWO line for output and SerialWire's SWDIO (along with the ARM Cortex's ITM channel 8) for input. This feature is useful for devices that need to use a serial port for character printing or command line interfacing (CLI) during prototyping or debugging but which don't ordinarily provide UART access through standard USART pins. Virtual UART I/O is made available through a TCP socket on the debug adapter via TCP port 4900, also hosted as the "Serial 0" tab on the Simplicity Studio's "Console" view (accessed by Launch Console action in Devices window). Additionally, strings printed to Virtual UART output will appear as "UART" events in Simplicity Studio's Network Analyzer in the Events pane of the Capture view.
Software Requirements for EFR32MG:
As of this writing, the following caveats exist around use of this feature: