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

[Artucas]

I have a periodical temperature measurements in my application. For that i set up a timer like this:

// Start application timers.
err_code = app_timer_start(m_temperature_timer_id, TEMPERATURE_MEAS_INTERVAL, NULL);
APP_ERROR_CHECK(err_code);

And my TEMPERATURE_MEAS_INTERVAL is defined as follows:

// Temperature measurement interval
#define TEMPERATURE_MEAS_INTERVAL APP_TIMER_TICKS(RTC_IRQ_PERIOD_MS, APP_TIMER_PRESCALER)

Here RTC_IRQ_PERIOD_MS = 5000. (With APP_TIMER_PRESCALER set to zero.) This configuration gives me measurement interval of 5s. So by changing RTC_IRQ_PERIOD_MS you can configure your timeout in milliseconds. Hope it helps.

[karan]

Thank you so much for your kind reply and its helpful for me have you worked on the battery measurement or battery notifications ?

[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?

[Artucas]

I haven't, but this link might help you: battery service

[karan]

Thanks aryan for your brief explanation the reason i would to change the presclar value is to measure the battery level and send the notifications to user if the battery level drops to 30 percent and so for doing that what is the best possible ways to do that?