WDT triggers DFU exit

[Arjun]

Hi,

I have an application that requires watchdog to run continuously. And from application I have code that jumps to the bootloader without device resetting using bootloader_util_app_start() API(example ble_app_hrs). This causes watchdog to trigger even though I have disabled all interrupts hence making dfu exit. Is there a way to disable watchdog. If not could you please suggest the best way to achieve a smooth jump to bootloader?

Thanks in Advance

[John]

Hi,

You should check out section 38 of the reference manual for more details. The watchdog timer will remain running through a soft reset, so even if you used a soft reset to get to your bootloader you would have the same issue. I ended up adding a watchdog service to the bootloader to prevent it from interfering with bootloading operations.

JD

[Susheel Nuguru]

wouldn't it be easier to stop the watchdog in this scenario?

[Arjun]

It looks like we cannot stop watchdog once enabled. Read in many forums and that seems to be the reason

[Susheel Nuguru]

oh yes, i missed to see that. In that case John's suggestion is the only thing that is left as a choice :)

[Arjun]

Hi John Dewitt, Can you share with me an example of what you did? Thanks for the answer. I think its better to have a WDT handler in the DFU.

[John]

Hi. Sure, I just changed the wait_for_events forever loop to look like:

    static void wait_for_events(void)
{
    for (;;)
    {
		NRF_WDT->RR[0] = WDT_RR_RR_Reload;					// Pat the watchdog
		
        // Wait in low power state for any events.
        uint32_t err_code = sd_app_evt_wait();
        APP_ERROR_CHECK(err_code);

        // Event received. Process it from the scheduler.
        app_sched_execute();

        if ((m_update_status == BOOTLOADER_COMPLETE) || 
            (m_update_status == BOOTLOADER_TIMEOUT)  ||
            (m_update_status == BOOTLOADER_RESET))
        {
			NRF_WDT->RR[0] = WDT_RR_RR_Reload;
            // When update has completed or a timeout/reset occured we will return.
            return;
        }
    }
}