Debugging with ITM not working with SWV in STM32CubeIDE

[evenlund]

I am successfully using all the SWV debugging functionality in STM32CubeIDE except for the ITM functionality, as described in UM1609 and in the advanced debugging videos on youtube from ST.

I have both tried overriding the "_write " function in main.cpp or replacing "__IO_putchar" with "ITM_SendChar" in syscalls.c, but I don't see any output when using printf and ITM port 0 (described in video 4 and section 4.3.5 in UM1609).

I have further tested sending output to ITM port 31, as described in video 5, but still cannot see any output.

Some details and further questions

• SWO is left unconnected - Do I need to connect the SWO to some other pin to make ITM work?
• I am running at 180 MHz clock speed - Is this too fast for ITM?
• Does it matter if I compile for cpp rather than c?
• Are there any benefits to updating an ITM port, like in video 5, rather than updating a global variable and observing the execution order by looking at a graph in a SWV Data Trace Timeline Graph or in CubeMonitor?
• Any further suggestions of why I can make all but ITM work for me with Nucleo-F446RE?

[evenlund]

I have tried ruling out a few things by copying the code from the youtube ST advanced debugging video series:

• I am running at 180 MHz clock speed - Is this too fast for ITM? I have tried setting this now to default 84 MHz, like in the video, but I get no difference. Edit: I forgot to include the _write function and it was working at 84 MHz.
• Does it matter if I compile for cpp rather than c? Not working for C either.

The advanced debugging capabilities in STM32CubeIDE is really impressive if i can make it work. Can someone test the ITM functionality on a different MCU or board? Preferably on a M4.

[evenlund]

Tested now also the original code from ST (http://bit.ly/AdvDebugMaterials) with my Nucleo-F722ZE on 216 MHz default system clock, but I still get no output from ITM. All other SWV functionality is working. What am I missing?

[TDK]

> SWO is left unconnected

Fairly sure SWO is used to transfer ITM information.

[Tesla DeLorean]

Check with STM32 Cube Programmer or ST-LINK Utilities, both have a SWV Viewer

There must be a common understanding of the clock speeds.

Print those clocks out, perhaps also pull the SWO divider value out.

Double check solder bridges on DISCO and NUCLEO boards, ensuring PB3/SWO get to the debugger, and the pin isn't reconfigured elsewhere.

Check RCC/GPIO registers.

[evenlund · Accepted solution]

I finally figured out that it was the clock speed that was the problem. I am not sure what the limit is for running ITM is, but it is working for 84 MHz and not on 180 MHz. I assume that the other SWV traces will also be inaccurate at high clock as data will be lost in transfer and not be shown in graphs and logs.

[Andre_k]

Updating to the ST-Link current latest version 3.14.5 fixed the issue for me. Try that first before attempting to downgrade your ST-Link. I have testet this with an STM32G491RE-Nucleo and STM32CubeIDE version 1.15.

Hope this helps 🙂

Edit: Clock speed should not be an issue, I have testet it at 170MHz. The clock is anyway prescaled down as shown in the upper left under "Clock Settings".