Skip to main content
Visitor II
March 17, 2025
Solved

STM32F407 Discovery Board UART1 not working

  • March 17, 2025
  • 2 replies
  • 764 views

DS1Z_QuickPrint1.pngGPIO STM serial test.jpg

I'm having the same problem on 2 different boards. I gen'd up a simple program using CubeMX and I'm only sending some data to both ports at the same time:

 

void StartTask02(void const * argument)
{
 /* USER CODE BEGIN StartTask02 */
 /* Infinite loop */
 int i;
 for(i = 0;i < DATA_SIZE;i++)
	 data[i] = i;
 vTaskDelay(1000);
 for(;;)
 {
 vTaskDelay(2);
	HAL_UART_Transmit(&huart1, &data[0], DATA_SIZE/5, 100);
	HAL_UART_Transmit(&huart2, &data[0], DATA_SIZE/5, 100);
 }
 /* USER CODE END StartTask02 */
}

 

I thought maybe one was a 'knock-off' because the LED's aren't colored while the other is.

    This topic has been closed for replies.
    Best answer by Pavel A.

    See the document for your board, page 22. https://www.st.com/resource/en/user_manual/dm00039084-discovery-kit-with-stm32f407vg-mcu-stmicroelectronics.pdf

    Pins PA9, PA10 are not free to use. They are connected to the green LED and USB.

    Before assigning pins, check that these pins are free to use - even if they are routed to connector.

    Try USART3 on TX PD8, RX PD9 

    2 replies

    Super User
    March 17, 2025

    Show circuit, what you connect to the boards, so its not only guessing...

    +

    On your scope pic : 50v/div + 5V/div -> about 30Vss + 15Vss signals , where you measure this ??

    Visitor II
    March 18, 2025

    I just had the scope probes hooked up to TX of UART1 & 2. I didn't bother to set the voltages.

    Pavel A.Answer
    Super User
    March 17, 2025

    See the document for your board, page 22. https://www.st.com/resource/en/user_manual/dm00039084-discovery-kit-with-stm32f407vg-mcu-stmicroelectronics.pdf

    Pins PA9, PA10 are not free to use. They are connected to the green LED and USB.

    Before assigning pins, check that these pins are free to use - even if they are routed to connector.

    Try USART3 on TX PD8, RX PD9 

    Visitor II
    March 18, 2025

    I think you may be right. In the manual, I found this:

    USB LD7: green LED indicates when VBUS is present on CN5 and is connected to PA9
    of the STM32F407VGT6

    dm00039084-discovery-kit-with-stm32f407vg-mcu-stmicroelectronics.pdf  on page 18/32