SDK15.0 DFU and WatchDog issue

[abe]

Hi, I apologize for the question renewal, that is the same as ticket "SDK15 DFU and WatchDog issue" (for my mistake I closed the discussion post!).

I have developed a custom board with NRF52840. I'm using the Secure BLE DFU bootloader from SDK15, but I have many troubles because my application has WatchDog enabled, and the DFU fails very often.
I also tried my application without WatchDog, and DFU works well.
I need to have WatchDog enabled in my application, then have you any suggests and/or solutions to solve this issue?

I'm using SDK15.0, the CRV is 2000 (#define NRFX_WDT_CONFIG_RELOAD_VALUE 2000)

Here above the source code I have on my application (copied from peripheral example on SDK)

//Configure WDT.
nrf_drv_wdt_config_t config = NRF_DRV_WDT_DEAFULT_CONFIG;
err_code = nrf_drv_wdt_init(&config, wdt_event_handler);
APP_ERROR_CHECK(err_code);
err_code = nrf_drv_wdt_channel_alloc(&m_channel_id);
APP_ERROR_CHECK(err_code);
nrf_drv_wdt_enable(); 

Many thanks for help

A. Barbieri - Como (Italy)

[AmbystomaLabs]

DFU is a second application.  If you enable WDT in your app and switch to DFU, then you have no mechanism for refreshing the WDT.  Hence you will get a WDT timeout and reset. So, you either need to shut down the WDT before you switch to DFU or put a WDT refresh routine in the DFU code to keep the WDT timer alive.

[abe]

I'm not shure to good understand ... to use the Wdog a DFU source code modification is needed?
Some little questions:
- the WDOG has shut down possibility? How? 
- where can I put the Wdog shut down (or the Wdog refresh) inside the DFU code?
Please help me!!

[Sigurd]

This feature was actually added in SDK 15.0, from the release notes, "Added watchdog support to the bootloader. If application had enabled watchdog before resetting to the bootloader, it is fed in the bootloader.".

But in SDK 15.2 release notes, we have that "Fixed a bug where the watchdog feeding in the bootloader did not happen during a certain FW activation.", so I would recommend testing with SDK 15.2, and see if you have the same issue there abe.

[abe]

But this solution needs SDK update and migration!! With new project tests and certifications!!
There are no other way to solve the issue only on DFU mode??

[Sigurd]

You should be able to fix it without migrating. In nrf_bootloader_wdt.c, try changing wdt_feed_timer_handler() so it look like this:

static void wdt_feed_timer_handler(void)
{
        NRF_LOG_INFO("Internal feed");
        wdt_feed();
}