Problem with low power delay when using APP_Timer

[Michael01101]

Hello,

at the moment we are trying to realize a low power delay with the usage of the APP_TIMER.

We need a low power delay over 10 seconds.

This is our attempt:

APP_TIMER_DEF(initTimer);
volatile bool run_init=false;

static void TimeoutInit(void * context)
{
    run_init=true;
}

static void lfclk_config(void)
{
    NRF_CLOCK->LFCLKSRC             = (CLOCK_LFCLKSRC_SRC_Xtal << CLOCK_LFCLKSRC_SRC_Pos);
    NRF_CLOCK->EVENTS_LFCLKSTARTED  = 0;
    NRF_CLOCK->TASKS_LFCLKSTART     = 1;
    while (NRF_CLOCK->EVENTS_LFCLKSTARTED == 0)
    {
        //Do nothing.
    }
    NRF_CLOCK->EVENTS_LFCLKSTARTED = 0;
}

static void timers_init(void)
{
    ret_code_t err_code = app_timer_init();
    APP_ERROR_CHECK(err_code);
}

int main(void)
{
    ret_code_t error_code;
    
    enable_DCDC();
    lfclk_config();
    log_init();
    timers_init();
    power_management_init();
    
    app_timer_create(&initTimer, APP_TIMER_MODE_SINGLE_SHOT,TimeoutInit);
    APP_ERROR_CHECK(error_code);
    app_timer_start(initTimer, APP_TIMER_TICKS(10000),NULL);
    APP_ERROR_CHECK(error_code);
    
    while(1)
    {
        if (run_init == true)
        {
            run_init = false;
            // DO ALL MY STUFF
            ...
        }
        idle_state_handle();
    }
}
            

Unfortunately, we still have about ~2mA during this 10 seconds of waiting.

We need to achieve ~300µA current draw during the delay.

Can anybody provide some help? What causes this high current draw during the delay?

Thank you very much in advance.

Best regards,

Michael

[Einar Thorsrud]

Hi Michael,

If you wait with just an RTC running (as is the case if you only use the app_timer), then you can get a sleep current of just a few micro amps. So there is clearly something else causing the current consumption here. That could either be some other part of your code that have enabled some peripherals/resources that have not been stopped, or other parts of your hardware. Can you explain more about your code and HW?

Einar

[Michael01101]

Hello Einar Thorsrud,

thank you very much for your reply.

It looks like that I fixed the issue:

NRF_CLOCK->LFCLKSRC

The wrong LFCLKSRC was set.

But I will do some further testing.

Thank you.

Best regards,

Michael