STM32F405 IWDG doesn't reset

Forum|Forum|5 years ago
November 4, 2020
5 replies
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I am having a problem where the IWDG seems to not reset the processor. I have setup a very simple project that enables the IWDG and then doesn't pet it - it should reset, but it doesn't. Running under the debugger or running standalone, it doesn't reset in either case. I can see that the IWDG RSTF is set in the RCC_CSR register. If I reset those bits using RMVF bit, the IWDG RSTF bit again gets set after the expected time. This makes me think that the independent watchdog is indeed going off, but for some reason the chip is just not resetting. This is such a simple thing it seems like, why doesn't it work?

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Best answer by waclawek.jan

Yes, it's a recurring theme here, although maybe more in the "software reset does not work" form.

JW

waclawek.jan

Super User

NRST pin pulled up hard?

JW

Elijah BrownAuthor

Associate II

Yes, it is connected to an external reset control chip which probably keeps that pin held high - would that keep it from resetting? I didn't think a watchdog reset would actually try and pull down that pin.

Elijah BrownAuthor

Associate II

You are right, the reset circuit diagram does suggest that holding that pin high would prevent a reset. Thanks for the suggestion, I believe this is the problem.