Watchdog reset during DFU

RE: Watchdog reset during DFU

Vincent44 — Mon, 18 Mar 2024 10:02:16 GMT

Hi Einar,

I set aside this issue to continue developping other parts of the project.

Now back to it, I no longer have issue with watchdog during DFU. Not tsure I modified some inits, kconfig, or anything else, but everything works as expected now.

Thanks.

RE: Watchdog reset during DFU

Einar Thorsrud — Tue, 12 Mar 2024 14:41:03 GMT

Hi,

I have been looking more into this and testing, but I am not able to reproduce it with nRF Connect SDK 2.5.2 (currently the latest). Which SDK version are you using?

(Note that BOOT_WATCHDOG_FEED is enabled by default if the watchdog is enabled, and as mentionned it reads the WDT registers so no configuration is needed, so normally this is not something you need to think about at all.)

RE: Watchdog reset during DFU

Einar Thorsrud — Tue, 12 Mar 2024 09:38:56 GMT

Hi,

I am sorry for the late reply.

[quote user="Vincent44"]

If I increase the watchdog to 35 sec, I have no problem.

While increasing the timer is acceptable for my application, I have the feeling that it's just a solution to move around the initial problem

[/quote]

I agree. The watchdog should be fed in between writing chunks, so ther seems to be an issue here. I need to look into it and get back to you.

[quote user="Vincent44"]Is there any specific configuration to have on the watchdog ?[/quote]

No, feedign of the watchdog should work out of the box when enabled (it is possible to read all relevant information direclty from the WDT peripheral registers, so configuration is not needed).

RE: Watchdog reset during DFU

Vincent44 — Wed, 06 Mar 2024 15:38:32 GMT

Thanks for you quick reply.

The overall process to move the app to primary slot seems to take ~25 sec.

If I increase the watchdog to 35 sec, I have no problem.

While increasing the timer is acceptable for my application, I have the feeling that it's just a solution to move around the initial problem. Let's say that in the future my new image is larger and requires more time to be swapped, what value should I use ?! Isn't that the whole point of CONFIG_BOOT_WATCHDOG_FEED, to take care of the WDT while in the bootloader ?

I wasn't able to find much details on this topic, aside than using CONFIG_BOOT_WATCHDOG_FEED. Is there any specific configuration to have on the watchdog ? Should it be the Zephyr watchdog (https://developer.nordicsemi.com/nRF_Connect_SDK/doc/latest/zephyr/hardware/peripherals/watchdog.html#c.wdt_install_timeout), the nrf_wdt ( https://developer.nordicsemi.com/nRF_Connect_SDK/doc/latest/nrfx/drivers/wdt/driver.html) ?

Thanks

RE: Watchdog reset during DFU

Einar Thorsrud — Wed, 06 Mar 2024 13:54:01 GMT

I am not able to give an exact number. What happens if you test with longer timeouts?

RE: Watchdog reset during DFU

Vincent44 — Wed, 06 Mar 2024 13:19:42 GMT

I use a 10 sec timeout. Is that too short ?

I work with encrypted images, so the swap takes a bit more time than for a non-encrypted.

RE: Watchdog reset during DFU

Einar Thorsrud — Wed, 06 Mar 2024 13:16:11 GMT

Hi,

You should not have to do anything else. With this, the watchdog is feed at strategic places in MCUboot with MCUBOOT_WATCHDOG_FEED(). Which timeout (reload value) do you use for the watchdog? It if it too short, you can try with a longer timeout.