How do I configure a NUCLEO-L4A6ZG LPUART1 to work with the ST-LINK Virtual COM port?

[JKo]

I've been trying to get the Virtual COM port from the ST-LINK on a NUCLEO-L4A6ZG working for 2 days now without luck. I've had no problem configuring the UART3 on a NUCLEO-F429ZI to work with the Virtual COM port. Only thing different is that the former is on the LPUART and the later is on the usual USART/UART. I've accounted for the different Baud Rate Register factor. How does the UART on the F103 of the ST-LINK detect the speed of the UART from the main board? Is it the UART on the ST-LINK restricted to a particular set of parameters? I've tried 115200,N81 and numerous other baud rates from 2400 and up without luck.

On the same NUCLEO-L4A6ZG I am able to configure the UART2 for successful communication to another board but the solution for the LPUART1 on this board eludes me.

I don't think I'm doing anything special with the LPUART1 on this board. In fact the NUCLEO-WL55JC1 I have also uses LPUART1 connected to the virtual com port and I have that working without issues.

How does the ST-LINK's F103 UART detect what baud, word length, stop bits, and parity is being used by the main board?

[Mike_ST]

Hello,

LPUART1 is on GPIOG Pins 7 and 8, and without seeing your code, I would say you don't activate GPIOG pins that are relying on VDDOI2 power.

Please call  HAL_PWREx_EnableVddIO2(); function.

[JKo]

Thanks! That was it! I totally overlooked the PWR control component. I assumed my predecessor took care of such things on this when bringing up this MCU and I didn't find any bread crumb reminders in UM2179 nor RM0351 when reading the GPIO and LPUART portions that this needed to be done.