Implementing IWDG in sleep mode

[Nico3]

I implemented IWDG  reset having counter of  12 second and am  refreshing it using HAL_IWDG_Refresh(&hiwdg) in while loop. 

Everything is working as expected. But now the issue is when I implement sleep mode. 

The processor will be in sleep and wakeup by interrupt. So if processor doesn't wakeup within 12 second then HAL_IWDG_Refresh will not be executed.

[Danish1]

What do you want to happen?

How might you distinguish between stuck crashed asleep and operating correctly asleep?

One approach would be to have a periodic wakeup driven by a timer or the RTC, when you do a quick health-check and if things are good then refresh the watchdog.

Another approach would be to stop the watchdog from running, but for that you need to go through a reset cycle. So your startup-from-reset code would have to distinguish between intentional-reset-to-stop-watchdog-prior-to-sleep and reset-to-start/operate-normally.

[Nico3]

Dear Danish, 

I would prefer to implement first option. 

"One approach would be to have a periodic wakeup driven by a timer or the RTC, when you do a quick health-check and if things are good then refresh the watchdog"

Please suggest how to do quick health check as you suggested.

 

 

 

[Sarra.S]

Hello @Nico3, 

As @Danish1, using an RTC to wake up the MCU is a simple approach to consider! 

This Community article could be a good starting point!

 

 

[Issamos]

Hello @Nico3 

I think that you should use a timer to interrupt every 12s and add the HAL_IWDG_Refresh function to the TIMER interrupt function to make sure that the command is executed directly after the wake-up from sleep mode using the TIMER interruption.

Hope this is helpful. If your question is answered please check this answer as best answer to be diffused.

Best regards.

II

[Piranha]

1. Broken general low-power mode code.
2. Broken Stop mode code.
3. Broken RTC wake-up.

The code in knowledge base article you linked has all of those flaws. Does ST think it is OK to present everywhere a completely broken code, ignore almost all of the bug reports and pretend all of those issues do not exist?

[Piranha]

I didn't create this topic, apparently @KDJEM.1 did. It was a post there:

https://community.st.com/t5/stm32-mcus-embedded-software/implementing-iwdg-in-sleep-mode/m-p/587178

In addition I don't think this should be a separate topic, because all of the issues already are reported in the three linked topics. Also the title "Re: Implementing IWDG in sleep mode" is now not appropriate and, of course, it is pre-pended with the useless/harmful e-mail style "Re: " stupidity.

@Lina_DABASINSKAITE , what is going on here?