Nucleo-L475VGT6 : VCP (USART2) sends nothing – LED blinks, download OK, no garbage either

[emna]

Hello everyone,

I'm facing a very frustrating issue with USART2 on my Nucleo-L475VGT6 board using the built-in ST-LINK Virtual COM Port.

What works: - ST-LINK is detected (COM3 appears, Windows sound plays on connect)

- Code downloads successfully (no error in CubeIDE console)

- LED blinks (proof that main() is reached and while(1) is running)

- HAL_UART_Transmit is called 

What does NOT work:

- Nothing appears in any terminal: MobaXterm, PuTTY,  PowerShell serial reader

- No garbage, no partial characters, just black screen

- Same behavior in Run mode (no breakpoint) and after physical Reset button

MY code:

/* USER CODE BEGIN 0 */
uint8_t tx_buff[]={0,1,2,3,4,5,6,7,8,9};
/* USER CODE END 0 */

while (1)
{
 /* USER CODE END WHILE */
 
 /* USER CODE BEGIN 3 */
 HAL_UART_Transmit(&huart2, tx_buff, 10, 1000);
 HAL_Delay(10000);
}

What am I missing? Is there a jumper / solder bridge I forgot on Nucleo-L475VGT6 for VCP? Or is there a known bug with USART2 VCP on L4 series?

Thank you very much for any hint!

---

Edited to apply source code formatting - please see How to insert source code for future reference.

[TDK]

> Nucleo-L475VGT6

This is not a board that exists. Perhaps you meant Nucleo-L476VGT6?

Are you using PA2/PA3?

You're sending non-ascii characters. How are you viewing them? Most terminal software will discard them. Perhaps send "Hello world\n" instead.

[Peter BENSCH]

Welcome @emna, to the community!

There is no NUCLEO-L475VG, but you probably mean the B-L475E-IOT01A, which already has the status NRND (Not Recommended for New Designs). Anyway, if that's correct, the the debugger ST-LINK/V2-1 is not connected to USART2, but to USART1 (see the schematics).

Hope that answers your question?

Regards
/Peter

[Andrew Neil · Accepted solution]

As the others have said, make sure you're using the pins which are physically connected to the ST-Link's VCP - see the board's User Manual and/or Schematics for details.

CubeMX should also show which pins are connected to the ST-Link's VCP.

[emna]

Thank you very much for your quick replies and for welcoming me to the community

I have  installed the official ST-LINK driver , and configured PB6 and PB7 AS TX and RX PINS,

everything is stable now on USART1 . Thank you so much for your help it really guided me to check the right things in the manual and schematic.

[mƎALLEm]

@emna 

Please accept as solution the post that answred your original question.

Thank you