RTC1 timer reset after sleep

[makouda]

I configured my system to sleep after inactivity time.

  nrf_gpio_cfg_sense_input(WAKE_UP, NRF_GPIO_PIN_NOPULL, NRF_GPIO_PIN_SENSE_HIGH);
    err_code = sd_power_system_off();

when the system wake up from sleep (I use external acceleromter to wake up the system), the RTC1 timer value reset !!!

I use the following method the read RTC1 timer

uint32_t ticks_per_second;
    app_timer_cnt_get(&ticks_per_second);

how can I prevent the RTC1 timer from reset at sleep

[Susheel Nuguru]

Wakeup from system off (not WFE) )will cause a system reset and hence will reset almost all of the peripherals (exceptions are RAM and few registers). RTC will also be rest on wakeup from system off.

[Susheel Nuguru]

system sleeping is executing ARM instruction __WFE (also called system idle) and SYSTEM OFF is deepest power state set by NRF_POWER->SYSTEM_OFF register. These two are different things. RTC will keep on running in system_idle state even after it wakes up, but, in system_OFF state, it does not.