Dfu not sucess when app init and enable wdt,although I feeddog and disable the wdt

[Roger huang]

Dear Nordic

my SOFT DFU fail when I init the WDT, but I have feeddog and disable the WDT, like below:

static bool app_shutdown_handler(nrf_pwr_mgmt_evt_t event)
{
switch (event)
{
case NRF_PWR_MGMT_EVT_PREPARE_DFU:
NRF_LOG_INFO("Power management wants to reset to DFU mode.");
// YOUR_JOB: Get ready to reset into DFU mode
//
// If you aren't finished with any ongoing tasks, return "false" to
// signal to the system that reset is impossible at this stage.
//
// Here is an example using a variable to delay resetting the device.
//
// if (!m_ready_for_reset)
// {
// return false;
// }
// else
//{
//
// // Device ready to enter
// uint32_t err_code;
// err_code = sd_softdevice_disable();
// APP_ERROR_CHECK(err_code);
// err_code = app_timer_stop_all();
// APP_ERROR_CHECK(err_code);
//}
break;

default:
// YOUR_JOB: Implement any of the other events available from the power management module:
// -NRF_PWR_MGMT_EVT_PREPARE_SYSOFF
// -NRF_PWR_MGMT_EVT_PREPARE_WAKEUP
// -NRF_PWR_MGMT_EVT_PREPARE_RESET
return true;
}

NRF_LOG_INFO("Power management allowed to reset to DFU mode.");
nrf_drv_wdt_feed();
nrf_wdt_int_disable(NRF_WDT_INT_TIMEOUT_MASK);
//nrf_wdt_int_enable(NRF_WDT_INT_TIMEOUT_MASK);
return true;
}

I don't know why nrf_wdt_int_disable is un-useful.

but if I don't init wdt in main, dfu is ok.

thanks for support.

Roger Huang

[Vidar Berg]

Hi,

It's not possible to stop the WDT in SW after it has been started. nrf_wdt_int_disable() may be used to disable the TIMEOUT interrupt, but it will not stop the WDT. 

Which SDK version are you currently using?  Bootloader from SDK 15.0.0 and later should reload the WD automatically. 

Best regards,

Vidar

[Roger huang]

I use SDK nRF5_SDK_14.2.0_17b948a, so bootloader have reload WD.

but what's the relation of this question, when I init the WD in app, will not entry to dfu successly?

[Roger huang]

so if I init the WD in app, after go to dfu, I must feedwdt of app?

[Vidar Berg]

The WD will continue to run in DFU mode, so you will get a reset if you don't feed it in your bootloader code as well. In SDK 14 there is also the "while (nrf_clock_lf_is_running())" statement that will prevent the bootloader from booting the app as long as the WD is running, please take a look at this thread here for more details: https://devzone.nordicsemi.com/f/nordic-q-a/30677/bootloader-doesn-t-load-application-with-watchdog/