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av500
av500
Associate II
Mar 25, 2026 7:12 AM UTC
Solved

CubeMX2, allow to use SWD without SWO

when you enable SWD in CubeMX2 it automatically blocks the SWO pin as well (tested using C531FBP6), but I only need SWCLK / SWDIO to debug. please add a way to disable the use of SWO.

Saket_OmBest answer
ST Technical Moderator
Jun 25, 2026 8:50 AM UTC

Hello ​@av500 

The issue has been solved in the new STM32C5 Ecosystem release 2.1.0. 

In order to give better visibility on the answered topics, please click on 'Best answer' on the reply which solved your issue or answered your question. Saket_Om
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15 replies

Oussama_TROUDI
Oussama_TROUDI
ST Technical Moderator
Mar 26, 2026 4:24 PM UTC

Hello @av500 and welcome to the ST community,

I’m currently checking this with the dev team and will get back to you as soon as I have an update.

In order to give better visibility on the answered topics, please click on 'Accept as Solution' on the reply which solved your issue or answered your question.
    Karl Yamashita
    Karl Yamashita
    Super User
    Mar 26, 2026 7:49 PM UTC

    You can right click and reset the pin state so it's no longer SWO.

    If a reply has proven helpful, click on Accept as Solution so that it'll show at top of the post.CAN Jammer an open source CAN bus hacking toolCANableV3 Open Source
    av500
    av500Author
    Associate II
    Mar 26, 2026 9:20 PM UTC

    sorry, but I cannot, as you can see, "Reset Pin State" is disabled

    Screenshot_20260326_221746.png 

    Karl Yamashita
    Karl Yamashita
    Super User
    Mar 26, 2026 9:24 PM UTC

    Must be a bug on your selected part. I was able to do it on the C562RE

    If a reply has proven helpful, click on Accept as Solution so that it'll show at top of the post.CAN Jammer an open source CAN bus hacking toolCANableV3 Open Source
    Karl Yamashita
    Karl Yamashita
    Super User
    Mar 26, 2026 10:35 PM UTC

    It looks like if I select as a Board project with the C562RE, i am able to reset the SWD pins.

    If i create as an MCU project with C562RE, I can't reset the pins.

    If a reply has proven helpful, click on Accept as Solution so that it'll show at top of the post.CAN Jammer an open source CAN bus hacking toolCANableV3 Open Source
      av500
      av500Author
      Associate II
      Mar 26, 2026 10:47 PM UTC

      yes, when you open the C652 NUCLEO board, the 3 SWD pins are reserved and can be reset, but once debug is configured, you cannot reset any of them...

        Karl Yamashita
        Karl Yamashita
        Super User
        Mar 26, 2026 11:16 PM UTC

        @av500 @Oussama_TROUDI 

        I see now, I didn't Activate the SWD. Because it was highlighted and labeled when the project was opened, I assumed it was enabled. I didn't look at the legend.

         

         

        If a reply has proven helpful, click on Accept as Solution so that it'll show at top of the post.CAN Jammer an open source CAN bus hacking toolCANableV3 Open Source
        Saket_Om
        ST Technical Moderator
        Mar 30, 2026 1:34 PM UTC

        Hello @av500 

        Thank you for bringing this issue to our attention.

        I reported this internally.

        Internal ticket number: CDM0061153

        In order to give better visibility on the answered topics, please click on 'Best answer' on the reply which solved your issue or answered your question. Saket_Om
        Watson_1058
        Watson_1058
        Associate
        Jun 12, 2026 10:40 AM UTC

        I meet the same issue, so the SWO pin is necessary for SWD debug mode? 

        Saket_OmBest answer
        ST Technical Moderator
        Jun 25, 2026 8:50 AM UTC

        Hello ​@av500 

        The issue has been solved in the new STM32C5 Ecosystem release 2.1.0. 

        In order to give better visibility on the answered topics, please click on 'Best answer' on the reply which solved your issue or answered your question. Saket_Om
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