nrf54L15 - WatchDog functionality in deep sleep.

[varsha@]

Hello, 

I am configuring the Watchdog Timer (WDT) on my custom device and observed that it gets disabled when the system enters Deep Sleep mode. This behavior prevents the device from resetting, even when the GRTC wake-up interval exceeds the watchdog feeding period.

I wanted to know a method to keep the watchdog active during Deep Sleep. The device should periodically wake up from Deep Sleep, feed the watchdog, and return to sleep. This cycle should continue until the defined sleep duration elapses, at which point the GRTC should trigger the final wake-up event. 

[Sigurd]

Hi!

As per, https://docs.nordicsemi.com/bundle/ps_nrf54L15/page/wdt.html#ariaid-title3 , Entering System OFF mode will stop and disable the watchdog.

[varsha@]

Hello, 

Thank you for your reply. 

Yes, I referred to the Data sheet. But I am working on a custom Board, and when I'm using deep sleep, the device gets hanged during sleep after a few hours of continuously working .For confirming this, I tried using Normal Sleep, and the device has been working continuously for almost 5 days now, without getting hanged. Is there a way to solve this?

 Is there a way to debug what is actually happening during deep sleep {using function sys_poweroff();}? 

[Sigurd]

varsha@ said:

 Is there a way to debug what is actually happening during deep sleep {using function sys_poweroff();}? 

No, you will wake the chip up again then.

Here you can see what wakes the chip up from System OFF mode:

https://docs.nordicsemi.com/bundle/ps_nrf54L15/page/pmu.html#ariaid-title4

[varsha@]

Hello, 

So, are there any reasons why the device can hang in deep sleep?

Are there any ways to avoid this issue?