Watchdog behavior while debugging

Question

Recently while debugging my application i noticed strange behavior: i set watchdog timer to restart application if my peripheral is not receiving any data for some time.

In normal way - it seems to work, but when debugger session is open it is not restarting my app.

Does watchdog work while debugging?

void wdt_init(void){
_timer = 0;

_connected = false;
_reload_enabled = true;

NRF_WDT->POWER = 1;
NRF_WDT->CONFIG = (WDT_CONFIG_HALT_Pause << WDT_CONFIG_HALT_Pos) | ( WDT_CONFIG_SLEEP_Run << WDT_CONFIG_SLEEP_Pos);
// Configure Watchdog.
//  a) Pause watchdog while the CPU is halted by the debugger.
//  b) Keep the watchdog running while the CPU is sleeping.

NRF_WDT->CRV = 10UL * 32768UL;      //ca 10 sek. timout
NRF_WDT->RREN |= WDT_RREN_RR0_Msk;  //Enable reload register 0
NRF_WDT->TASKS_START = 1;           //Start the Watchdog timer}

I am using QFAA C0 chip

Stefan Birnir Sverrisson · Accepted Answer

You are correct John, I was perhaps too quick to answer the question. For the first revision hardware of nRF51, the watchdog does not produce a reset while in debug mode. Your nRF51822QFAAC0/nRF51422C0 chip is the first revision hardware. However, it works with the second revision nRF51 hardware (e.g. nRF51822QFAAG0). The watchdog however stops when I set breakpoint in debug mode and stop the code execution for the second revision hardware. When I remove the breakpoint and continue execution, the watchdog resets the chip. For the first revision hardware, I can set a breakpoint and halt code execution, but the watchdog still does not work in debug mode, it does not reset the chip when I remove the breakpoint and continue execution. So, yes I aggree, PAN issue #38 needs some clarification