Skip to main content
wjian.2
wjian.2
Associate III
August 17, 2023
Solved

stm_h747disco uart

  • August 17, 2023
  • 5 replies
  • 2389 views

If i use the serial interface USART1 HAL_UART_Transmit()( is directly available as a Virtual COM port of a PC connected to STLINK-V3E USB connector CN2) could show in com9 in pc, but uart8(D0/D1) in com9 didn't show anything, This result should be right o bad? if i use putty which port should be for uart8?

This topic has been closed for replies.
Best answer by Peter BENSCH

When you connected your STM32H747I-DISCO to the PC, the PC selected a free COM port under which you find the VCP with the DISCO communication and in your case this was obviously COM9.

Since UART8 of the DISCO is not connected to the PC, but according to your last statement to the Arduino (which was not mentioned at the beginning), you will not find UART8 as a COM port in the PC.

Maybe you could use RS232-USB converters to sniff the UART connection between DISCO and Arduino. With the RX input of such a converter you could e.g. monitor the line UART8_TX and check what is happening on the TX channel. For monitoring in both directions you need the RX inputs of two such converters: one for UART8_TX and one for UART8_RX. The converter(s) can then be connected to your PC via a free USB port and should then be found with terminals such as PuTTY.

5 replies

Peter BENSCH
Peter BENSCH
ST Technical Moderator
August 17, 2023

On the STM32H747I-DISCO, USART1 is permanently connected to the ST-LINK (USART1_TX / T_VCP_TX, USART1_RX / T_VCP_RX), as you can see in the schematics. For this reason, if you want to have another VCP on the same USB line as the ST-LINK, you will not succeed with other ports without changing the hardware.

Hope this helps?

Regards
/Peter

In order to give better visibility on the answered topics, please click on Accept as Solution on the reply which solved your issue or answered your question.
wjian.2
wjian.2Author
Associate III
August 17, 2023

How could i know HAL_UART_Transmit() in sending right information with uart8 ,only for osciloscopio in the Pin o could use putty with some port special?

Peter BENSCH
Peter BENSCH
ST Technical Moderator
August 21, 2023

I still don't fully understand your problem. But I guess you want to communicate via UART8 in addition to USART1 (via VCP)?

PuTTY is a terminal emulator that runs on a PC. To connect to UART8 of the STM32H747I-DISCO, you must first successfully connect the PC to UART8_TX and UART8_RX. To do this, you will need an adapter that converts these two 3.3V lines to RS232 level or convert them to USB. In the simplest case, any RS232 USB adapter can do this.

Which port you then use to find UART8 with e.g. PuTTY has nothing to do with the STM32, but depends on the PC operating system used.

In order to give better visibility on the answered topics, please click on Accept as Solution on the reply which solved your issue or answered your question.
wjian.2
wjian.2Author
Associate III
August 21, 2023

my question is i want to send array of char to arduino ,but arduino do not receive nothing, i want to check if it is already send this message, for example i could see usart1 in com9 but uart8 i dont know where i can check this message

Peter BENSCH
Peter BENSCHBest answer
ST Technical Moderator
August 21, 2023

When you connected your STM32H747I-DISCO to the PC, the PC selected a free COM port under which you find the VCP with the DISCO communication and in your case this was obviously COM9.

Since UART8 of the DISCO is not connected to the PC, but according to your last statement to the Arduino (which was not mentioned at the beginning), you will not find UART8 as a COM port in the PC.

Maybe you could use RS232-USB converters to sniff the UART connection between DISCO and Arduino. With the RX input of such a converter you could e.g. monitor the line UART8_TX and check what is happening on the TX channel. For monitoring in both directions you need the RX inputs of two such converters: one for UART8_TX and one for UART8_RX. The converter(s) can then be connected to your PC via a free USB port and should then be found with terminals such as PuTTY.

In order to give better visibility on the answered topics, please click on Accept as Solution on the reply which solved your issue or answered your question.
Terms & ConditionsAccessibility statement