app_timer_cnt_get() always returns 0x0018000 (SDK12.1.0)

[Brendan S]

I'm trying to use app_timer_cnt_get() to implement an RTC Calendar system on a Gigawit module (nRF51822).

I have a test app_timer that has presacler=0 and period=3 seconds. The callback works as I toggle a LED, and it toggles every 3 seconds.

The code uint32_t this_count = app_timer_cnt_get(); shows a value of 0x00018000 when I set a breakpoint after the call to app_timer_cnt_get().

Why does it not increment? RTC1 and the timer is obviously working and counting, and app_timer_cnt_get() eventually return NRF_RTC1->COUNTER;

Is the counter automatically reset to zero? I can't imagine so if multiple timers are used with APP_TIMER.

I've tried enabling RTC1 in sdk_config.h, but app_timer was working without that anyway.

I've also tried enabling APP_TIMER_KEEPS_RTC_ACTIVE in sdk_config.h. I think I need this anyway for my Calendar implementation (for log timestamps), however it didn't make any difference.

Any help or suggestions greatly appreciated !!

Brendan.

[Brendan S]

app_timer_cnt_get() is working ok. Putting a breakpoint in the handler causes the processor to reset on resumption and RTC1 was being reset/reinitialised.

Reading the timer count and storing in a global variable, and watching the variable in a live watch window, I could see the variable incrementing by 0x18000 every 3 seconds.

Thanks Ole for the heads up.

Brendan.