STM32L562E-DK VCP UART. TX OK. RX NO

Llope.3 · ‎2021-09-09

Hello, guys!

My name is Luis and I bought the board STM32L562E-DK for testing purposes for a new project.

I have been executing many examples based on freertos and I am very happy on how the STM32L562Q could be my solution in a future project.

However, with one of my own last test, where I want to pass files via USB (using the USB port ST-LINK used as VCP Uart) to MCU and save them on the external memory using OCTOSPI, I have set up the USART1 and I watch that the transmission is working properly but the reception is not working.

I have configured the USART1 as same as other UART that I am using (UART4) but there is something wrong because I can't receive any byte.

Please, could you help me? Is the problem on that I am assuming that the VCP Port is equal as other normal UART?

Many thanks on advance!

PS: I have attached the USART1 configuration.

EDIT: Also, I attach the board resistors configuration that shows that the VCP lines are enabled.

BR

Bruno_ST · ‎2021-09-10

Hello @Llope.3 ,

Your configuration looks good. To be sure there is no HW problem, i may check and example with VCP RX/TX as it is very common communication we use on such board. The only trick is the level shifter (part U37) on USART1TX that guaranty good communication between L5@1.8V to STLINK@3.3V (depends of JP3)

Best regards

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Pavel A. · ‎2021-09-11

Please see this thread. Try their workaround.

Llope.3 · ‎2021-09-13

Thank you, Bruno and Pavel.

I have checked the board and it seems to be ok. The JP3 is connected to use 3V3. I measured the voltage on U37 and on both sides the Vdd is 3V3. Also I have checked the ESD protection on U45 and it seems to be ok. So, I think that the problem is not hardware. Even I use a wired bridge between pads 13 and 14 of connector CN8 (T.VCP_RX & T.VCP_TX) and it didn't trigger the ISR on USART1 (I have writen a simply blink led code on the isr for any character recepction). All these test, I have made them without debugging using ST-LINK to asure that the debugging part was not the problem.

In reference to the workaround pointed by Pavel, I have tested it and It doesn't work for me :(

Note: The transmission works in all cases. I receive strings without problems at the serial terminal on PC.

Sure I am missing something on my code to get it working properly for use VCP COM.

Many thanks!