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From my understanding of the schematic the EFR32BG22 USART1 goes to the on-board debugger and is presented as a VCOM UART - the pins are also wired to the Simplicity connector as SI_UART.

Is it possible to disable the VCOM UART so that I can use the Simplicity connector to connect to some other hardware I have to USART1 ?

If it means adding a wire or removing a resistor or some other small mod then I am happy to make that.

BTW I would still like to keep the USB debug connection for the JLINK loading/debugging if possible.


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  • I think that's possible but some hardware rework is needed. In fact, if you try to disable the debug functionality of the example project (will not route the USART1 Tx/Rx pins to PA05/PA06), and then input some serial data to EXP_HEADER12, you should able to get the data output in the console of the VCOM port.
  • I ended up removing a resistor to isolate the inbound serial from the USB. This prevented two transmitter outputs fighting, i.e. between the tx out of the USB into the EFR32 USART1 receiver and the output from my external transmitter. Seemed to work fine for me.