STM32H7 dual core -- watchdog not firing?

[Ray, KF6GPE]

So, this is a weird one. We're attempting to bring up watchdog timers on both cores of our product.

We're not seeing the CM4 WWDG watchdog fire when we intentionally lock the CM4 in a while loop with no refreshes to the watchdog timer. (I haven't tried the CM7 core yet with similar code).

I understand that each core has a watchdog timer (well, two, the WWDG and the IWDG). Right now to begin with we are enabling the watchdog on only a single core, the CM4 core, like so:

__HAL_RCC_WWDG1_CLK_ENABLE();

 

/* Clear reset flags in any case */

__HAL_RCC_CLEAR_RESET_FLAGS();

 

/* Enable system wide reset */

HAL_RCCEx_WWDGxSysResetConfig(RCC_WWDG1);

 

// These numbers result in a timeout of about 300ms

g_watchDogHandle.Instance = WWDG1;

g_watchDogHandle.Init.Prescaler = WWDG_PRESCALER_128;

    g_watchDogHandle.Init.Counter = 0x7F;

    g_watchDogHandle.Init.Window = 0x7F;

g_watchDogHandle.Init.EWIMode = WWDG_EWI_DISABLE;

 

#ifdef DEBUG

//return;

#endif

 

HAL_WWDG_Init(&g_watchDogHandle);

 

We enter the while loop on one screen of our application, using just a 

while (true) {}

 

I've verified with the debugger that we're both entering the watchdog initialization code, as well as the while loop, and let let it sit for well over ten minutes.

On a lark, I enabled the EWIMode and put a breakpoint in  WWDG_IRQHandler(), and don't see that entered either.

This seems very, very weird. Am I missing something?

[TDK]

Does the WWDG_CR register indicate that it's active? Is the counter counting down?

[Tesla DeLorean]

What are you doing with the NRST pin?

What's it connected too? Driven High, or driven by some other device or circuit?

[Ray, KF6GPE]

Thanks to both of you for the suggestions!

It was actually a much dumber mistake on my part --- I was trying to enable the CM7 watchdog on the CM4 core. For the next person on the internet who runs into this, here's some code that works:

	__HAL_RCC_WWDG2_CLK_ENABLE();

	/* Clear reset flags in any case */
	__HAL_RCC_CLEAR_RESET_FLAGS();

	/* Enable system wide reset */
	HAL_RCCEx_WWDGxSysResetConfig(RCC_WWDG2);

	// These numbers result in a timeout of about 300ms
	g_watchDogHandle.Instance		= WWDG2;
	g_watchDogHandle.Init.Prescaler	= WWDG_PRESCALER_128;
 g_watchDogHandle.Init.Counter	= 0x7F;
 g_watchDogHandle.Init.Window	= 0x7F;
	g_watchDogHandle.Init.EWIMode	= WWDG_EWI_DISABLE;

#ifdef DEBUG
	return;
#endif

	HAL_WWDG_Init(&g_watchDogHandle);