Blue and Black Pill SWO debugging

[mkigor]

Split from STM32H5 SWO debugging.

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I want use SWO pin like standalone debug. Send data by "ITM_SendChar('A');" and want to read data from SWO pin by USB-UART dongle, SWO pin => Rx pin UART-USB on PC.

I try blue and black pill (STM32F103 and STM32F411), in stm32 cube ide I configured SysremCore->SYS->Debug: Trace Asynchronus Sw. In "Debug configuration" is Enable for SWV and clock core 8Mhz (SYSCLK and HCLK = 8MHz).

In main sycle:

  while (1)
  {
    /* USER CODE END WHILE */
	  HAL_GPIO_TogglePin(Led_GPIO_Port, Led_Pin);
	  HAL_Delay(1000);
	for (int i = 0; i < 10000; ++i) ITM_SendChar('A');
	  HAL_GPIO_TogglePin(Led_GPIO_Port, Led_Pin);
	  HAL_Delay(1000);
    /* USER CODE BEGIN 3 */
  }

LED is blinking, but SWO pin out is NO SIGNAL (Checking by oscillograph).
Where is it possible problem?

[Andrew Neil]

Note that Blue & Black Pills are not ST products, and likely do not have genuine STM32 chips.

In the other thread, @AScha.3 said that it's important to end your output with \r\n - did you try that?

[mfgkw]

you wrote:

> SWO pin => Rx pin UART-USB on PC

Are you sure this is correct?

I would expect to send from STM32-SWO via a pin labeled Tx or TxD to the PC. Maybe you want to double check the doc of your USB converter.

[Andrew Neil]

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@mfgkw wrote:

I would expect to send from STM32-SWO via a pin labeled Tx or TxD to the PC

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Really?

SWO = Serial Wire Output - so I'd expect it to go to RX (an input) on the PC (a DTE) ?

[mfgkw]

It will depend on how the developer of the converter looks on its baby.

The doc should tell...

[TDK]

> want to read data from SWO pin by USB-UART dongle, SWO pin => Rx pin UART-USB on PC.

The SWO signal is not a UART signal. This has no hope of working.

[AScha.3]

>and want to read data from SWO pin by USB-UART dongle, SWO pin => Rx pin UART-USB on PC.

This wont work.

Its more complex, than you are thinking : 

+

You can connect with the CubeProgrammer -> ST-link -> to the ITM :  then see SWV  -> SWO output:

+

>want to read data .. by USB-UART dongle, .. pin => Rx pin UART-USB on PC.

If you just want serial "debug" messages, use an UART at "some speed" .(I use 3 Mbit for this.)

Or the USB , as CDC device , so you can connect to a PC /USB directly. 

[Andrew Neil]

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@TDK wrote:

The SWO signal is not a UART signal. 

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In principle, it could be:

https://developer.arm.com/documentation/ddi0314/h/Serial-Wire-Output/SWO-trace-port/Physical-pin-protocol#:~:text=Manchester%20encoding%20example-,UART%20encoding,bit%20%5B11%5D%20of%20the%20Device%20ID%20Register%2C%200xFC8%2C%20is%20set,-.%20It%20is%20enabled

Do (any) STM32 support that ?

@mkigor Generally, it's connected to the debug probe; eg, ST-Link.

[AScha.3]

>Do (any) STM32 support that ?

Yes.  On the "clone" ST-link V2 just need to connect to PB7 , UART1 Rx , to get the SWO data.

(The pic i showed, with CubeProgrammer connected to a H743 cpu showing SWV data, is made with an modified 

ST-link V2 , working 100% reliably at 2 Mbit. With a ST-link V3 higher speed is no problem.)

here with cmsis-DAP , also STM32F103 cpu :