STM32F767 Nucleo board printf to console

Question

For the last couple of days I have been trying to get printf to work to print a debug message to a STM32CubeIDE console. However, without any luck. I have gone through numerous forum threads and discussions and none of them appear to have fully solved this weird issue that is well known.

I have just generated a brand new project with STM32CubeMX and used a default configuration for the Nucleo board. I am just using a USB cable with a built-in ST-LINK to program the device.

So far, I have been suggested to add a few lines of code that apparently should have fixed the issue, but it didn’t:

#ifdef __GNUC__
#define PUTCHAR_PROTOTYPE int __io_putchar(int ch)
#else
#define PUTCHAR_PROTOTYPE int fputc(int ch, FILE *f)
#endif


PUTCHAR_PROTOTYPE
{
  HAL_UART_Transmit(&huart3, (uint8_t *)&ch, 1, 0xFFFF);

  return ch;
}

I have also included:

#include "stdio.h"

The actual code:

int main(void)
{
  /* USER CODE BEGIN 1 */
    uint8_t uart3_data[20] = "Hello from UART 3";
    uint8_t uart1_data[20] = "Hello from UART 1";
  /* USER CODE END 1 */


  /* MCU Configuration--------------------------------------------------------*/

  /* Reset of all peripherals. Initializes the flash interface and the Systick. */
  HAL_Init();

  /* USER CODE BEGIN Init */

  /* USER CODE END Init */


  /* Configure the system clock */
  SystemClock_Config();

  /* USER CODE BEGIN SysInit */

  /* USER CODE END SysInit */


  /* Initialize all configured peripherals */
  MX_GPIO_Init();
  MX_USART3_UART_Init();
  MX_USART1_UART_Init();
  MX_TIM10_Init();

  /* USER CODE BEGIN 2 */
  HAL_TIM_Base_Start_IT(&htim10);
  /* USER CODE END 2 */


  /* Infinite loop */
  /* USER CODE BEGIN WHILE */
  while (1)
  {
    /* USER CODE END WHILE */


    /* USER CODE BEGIN 3 */
      //Toggle_leds(GPIOB,GPIO_PIN_0,100);

      HAL_Delay(1000);
      printf("UART Printf Example: retarget the C library printf function to the UART \n\r");
      printf("** Test finished successfully. ** \n\r");
      HAL_UART_Transmit(&huart3,uart3_data, sizeof(uart3_data), 50); // just to see what happens

      //HAL_UART_Transmit(&huart1,uart1_data, sizeof(uart1_data), 50); // just to see what happens
  }
  /* USER CODE END 3 */


}

When I open up a terminal and connect to the device, I can see the messages coming as expected:

Enter image description here

However, I cannot understand why I am not able to see messages displayed on the STM32CubeIDE console. Am I missing some additional configuration?

Answer 1

I have managed to get it working. Those who are having the same problem, just follow these simple steps:

1. Add a custom _write function to syscalls.c or even main.c:

   int _write(int file, char *ptr, int len)
   {
     /* Implement your write code here. This is
        used by puts and printf for example */
     int i=0;
     for(i=0 ; i<len ; i++)
       ITM_SendChar((*ptr++));
     return len;
   }
   

2. In the debug configuration, enable the SWV tracing and set the core clock to the SYSCLK of your device (see the image below).

   

3. Debug your code and go to Windows → Show view → SWV → SWV ITM Data console

   Now you should have enabled SWV data console. Check the image below:

   

4. Open up the SWV ITM Data console settings and make sure the port 0 is ticked (see the image below):

   

5. When you run the code, make sure start tracing is enabled:

   

6. Have fun printing message to the console

A detailed guide on YouTube can be found in 5. Tutorial. Use Serial Wire Viewer (SWV/SWO) via printf to debug STM32 in STM32CubeIDE.

Unfortunately, there is still a hassle using this method. Every time you debug your code, you need to start tracing. There must be a simple method to display a message in the console without using the tracing.