what is the principle of converting Ticks in to seconds

[karan]

Hello

I am trying to change the ticks value of Battery measurement interval (ble_app-prox example) but i am not able to understand how the ticks period is measured based on what i understood from the example 1s is equal to 1000ms so totally we are setting it to120s then the ticks period is equal to 120000 if am wrong please correct me and explain me the correct method my aim to see the battery level changing based on the battery -measure_interval any help would be greatly appreciated

thankyou

[Susheel Nuguru]

Assuming you are using nRF51 and using APP_TIMER (RTC1).

You initialize the APP_TIMER using the prescaler. lets say that the prescaler is 0 then your timer generates 32768 ticks per second.

The macro given in app_timer.h converts the milliseconds to number of ticks.

#define APP_TIMER_TICKS(MS, PRESCALER)\
            ((uint32_t)ROUNDED_DIV((MS) * (uint64_t)APP_TIMER_CLOCK_FREQ, ((PRESCALER) + 1) * 1000))

Above you see that if MS = 120000 and prescaler 0, which is 120 seconds then you will get Ticks = ((120000*32768)/(0+1)*1000) rounded up to integer = 3932160 ticks. This is telling you that the timer will put 3932160 (0X3c0000) in RTC compare register and when RTC is started and is running for this many ticks, then it will be 120 seconds.

Does this answer your question?

[Susheel Nuguru]

prescaler is only needed to be changed if your timeout is more than 512 seconds. So here you you can use 0 as prescaler.

This below code can be used to see if ADC sample value drops to 30% and send notification.

    uint32_t err_code;
    uint16_t adc_value;
    uint8_t  percentage_batt_lvl;
    uint16_t batt_lvl_in_milli_volts;
    nrf_adc_conversion_event_clean();
    nrf_adc_stop();
    
    adc_value = nrf_adc_result_get();
    
    
    batt_lvl_in_milli_volts = ADC_RESULT_IN_MILLI_VOLTS(adc_value);
    
    percentage_batt_lvl     = battery_level_in_percent(batt_lvl_in_milli_volts);

    if(percentage_batt_lvl <= 30) {
    err_code = ble_bas_battery_level_update(&m_bas, percentage_batt_lvl);
    if (
        (err_code != NRF_SUCCESS)
        &&
        (err_code != NRF_ERROR_INVALID_STATE)
        &&
        (err_code != BLE_ERROR_NO_TX_PACKETS)
        &&
        (err_code != BLE_ERROR_GATTS_SYS_ATTR_MISSING)
       )
    {
        APP_ERROR_HANDLER(err_code);
    }
   }