understanding app_timer functionality

[Amit Chahar]

I am using app_timer to measure the time taken to execute a function. I am using ble_app_template code. As mentioned in the documentation, app_timer needs to initialize the LFCLK. It doesn't need to initialize a LFCLK if softdevice is used. But in the template, timer is created even before initialization of LFCLK. LFCLK is initialized in the ble_stack_init() which is after the timers_init() function.

1. Why is the timer working even without initializing LFCLK ?

   Source code is present here : github.com/.../silver-umbrella

   These are the code snippets :

    int main(void)
    {
        uint32_t err_code;
        bool     erase_bonds;
    
        err_code = NRF_LOG_INIT(NULL);
        APP_ERROR_CHECK(err_code);
    
    	timers_init();
        buttons_leds_init(&erase_bonds);
        ble_stack_init();
    	timeslot_sd_init();
        peer_manager_init(erase_bonds);
        if (erase_bonds == true)
        {
            NRF_LOG_INFO("Bonds erased!\r\n");
        }
        gap_params_init();
        advertising_init();
    		
        application_timers_start();
        err_code = ble_advertising_start(BLE_ADV_MODE_FAST);
        APP_ERROR_CHECK(err_code);
    
        // This is my function
    	cal_RPA_gen_time();
    		
        for (;;)
        {
            if (NRF_LOG_PROCESS() == false)
            {
                power_manage();
            }
        }
    }
   
    static void application_timers_start(void)
    {
        uint32_t err_code;
        //starting timer for 100 secs
        err_code = app_timer_start(m_app_timer_id, APP_TIMER_TICKS(100000, APP_TIMER_PRESCALER), NULL);
        APP_ERROR_CHECK(err_code);
    	SEGGER_RTT_printf(0, "Timer Started\n\n");
    }
   

2. If I call the function timers_init() after ble_stack_init(), timer is not started (no output on RTT viewer). Why ?

3. If I decrease the advertising interval to less than 20 ms i.e. min advertising interval, I get this kind of output for infinite time :

   0> Timer Created 0> Timer Created 0> Timer Created 0> Timer Created 0> Timer Created 0> Timer Created 0> Timer Created 0> Timer Created 0> Timer Created 0> Timer Created 0> Timer Created

   Is there any relation between advertising module and RTC1 ?

4. Also, when I try to set the gap address when timer is running, I am getting undesired output on RTT viewer. It seems like the timer get restarted when a new address is set. Why ?

This is the desired output :

This is the ouput I am getting :

Thanks in advance.