Watchdog reset after exactly 8000s while advertising with whitelist after previous successful connection

Question

Hi 
 On my device, after a successful (bonded) connection to a central, if I then turn off BLE on that central, my device moves through fast advertising and slow advertising (with whitelist) as expected. I can reconnect at will, however if I leave EXACTLY 8000 seconds (about 2 hrs, 13 mins) WITHOUT turning BLE back on on said central, then the NRF52832 WD resets. 
 At the moment I am detecting and handling this situation over the wire (SPI), but it would be rather better if it did not occur. The 8000 seconds is FULLY deterministic, and its too round a number to be some fluke, it must be deterministically driven by something! 
 SDK is 15.2, Soft Device is S132 (s132_nrf52_6.1.0_softdevice.hex) 
 Wondered if someone had an idea why this might be happening? 
 I have read about whitelisting and identify keys and a bug that exists in the Nordic SDK around the use of these? Maybe someone can tell me how I can turn off the use of Identity Keys, while retaining whitelisting? 
 Kind Regards 
 Karen

veletron · Accepted Answer

Hi 
 For anyone else suffering this issue, the answer from @H &aring;kon Alseth was the solution. Starting a timer with an empty handler will force the main loop to wake, and service the watchdog. This keeps the WDT functionality true to form eg if will still force a restart on a hang. 
 Thanks! 
 Karen 
 #include "app_timer.h"

// Local functions
static void Power_KickWdt(void *p_context);

// Periodic timer for allowing wakeup to ensure the watchdog timer is serviced. Required when BLE events are being serviced by the softdevice and there are no other application level events
#define WD_TIMEOUT_MS 60000
static app_timer_t m_WdtKickTimer_data __attribute__((aligned(4))) = {{0}};
static const app_timer_id_t m_WdtKickTimer = &m_WdtKickTimer_data;

/*
* Initialize power management
*/
void Power_Init(void)
{
// Initialise Nordic power management
APP_ERROR_CHECK(nrf_pwr_mgmt_init());

// Create and start our periodic wakeup timer
APP_ERROR_CHECK(app_timer_create(&m_WdtKickTimer, APP_TIMER_MODE_REPEATED, Power_KickWdt));
APP_ERROR_CHECK(app_timer_start(m_WdtKickTimer, APP_TIMER_TICKS(WD_TIMEOUT_MS), NULL));
}


/*
* Timer event handler for waking up to service the watchdog timer
* This routine does not kick the watchdog directly but allows the main loop to wake up and service it
*/
static void Power_KickWdt(void *p_context)
{
UNUSED_PARAMETER(p_context);
}

veletron · Answer

Hi. Still learning about what's going on here. If the WD reset code is removed, then it will run past the 8000 seconds, and the device remains connectable after the 8000 seconds. Additionally, if the power management code is removed from main () then the main loop will kick the WDT regularly as it wont sleep. Issue would appear to be that after 8000s, the SD quits kicking the WDT, and the WD then resets the device.

Watchdog reset after exactly 8000s while advertising with whitelist after previous successful connection

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