STM32H7B0 SWO over ITM doesn't work

[ypiotrp]

Hi!

I have a problem setting up Serial Wire Output over ITM. I followed every tutorial on the Internet (including this forum) and I still haven't made any progress.

I run the MCU on 280 Mhz:

In Pinout & Configuration -> DEBUG I configured Serial Wire as debug interface.

I've implemented my own _write() function as below:

int _write(int file, char *ptr, int len) {
  int DataIdx;
  for (DataIdx = 0; DataIdx < len; DataIdx++) {
    ITM_SendChar(*ptr++);
  }
  return len;
}

Next I just call printf inside some loop in main():

while(1) {
	  printf("counter = %d\n", counter++);
	  delay = 280000;
	  while(delay--);
  }

 My debug configuration looks like this:

And my SWV ITM configuration looks like this:

 

Please help me figure out how to get it up and running, because I'm getting frustrated after all my failures in tutorials.

Regards,

Piotr

[Pavel A.]

> Can you tell me something more about these 'subtle difference'?

If my memory serves, the ITM clock has additional divisor or multiplier. New ST tools know this and compensate.

[ypiotrp]

Which tools are you talking about? I use STM32CubeIDE v.1.9.0, CuveMX v.6.5.0

[RomainR.]

Hello @ypiotrp (Community Member) 

I successfully tested printf stdio redirected to ITM SWO on STM32H7A3VIT on custom board with STLinkV2-1 standalone and STM32CubeIDE v1.11.0 (but it also works with v1.9.0)

Here a screenshot of SWV ITM Data Console, SWV Data Trace Timeline Graph and Live Expression:

I can suggest to check following point:

• Debug is configured as Trace Asynchronuous Sw in CubeMx
• PB3 is connected to STLinkV2-1 Debugger on pin TDO-SWO (13)

If you have syscalls.c in your project, simply re define __io_putchar in the main.c.

/* USER CODE BEGIN 4 */
int __io_putchar(int ch)
{
 ITM_SendChar(ch);
 return(ch);
}
/* USER CODE END 4 */

Include stdio.h header and your code to printf and increment counter variable.

/* Private includes ----------------------------------------------------------*/
/* USER CODE BEGIN Includes */
#include "stdio.h"
/* USER CODE END Includes */

/* Private variables ---------------------------------------------------------*/
/* USER CODE BEGIN PV */
uint8_t counter = 0;
/* USER CODE END PV */

/* Infinite loop */
  /* USER CODE BEGIN WHILE */
  while (1)
  {
    printf("Counter= %d\r\n", counter);
    counter++;
    HAL_Delay(500);
    /* USER CODE END WHILE */
 
    /* USER CODE BEGIN 3 */
  }
  /* USER CODE END 3 */

In the debug configuration, enable SWV with the same CPU clock (280MHz)

Launch the debugger, open SWV ITM Data Console, enable ITM Stimulus Ports 0 (optionally set counter variable in data trace comparator)

Start Trace (red button icon) and resume debugger.

Good luck,

Best regards,

Romain,

[ypiotrp]

OK, I got it working!

Sorry for the trouble explaining it to me. It turned out I made a mistake and soldered SWO wire to wrong pin in my custom SWD plug.

I have the last question. Is there some simple way to access SWO data from localhost:61235? I tried connecting to that port using PuTTy but without any success :(

Regards,

Piotr

[AScha.3]

putty 🙂

you need a "debug" connection; new version of Cube programmer should work...(i didnt test)