getting millis from startup

Question

I need to count millis from nrf52 start 
 I have seen that all are using rtc1 but I did not find any example from which i can integrate it to my project.

Joakim Jakobsen · Accepted Answer

Hi Dhaval! 
 The reason that "all are using RTC1 ", is because the softdevice is using RTC0 . 
We do have an RTC example in the SDK that you can take a look at. 
Located at; sdk_location/examples/peripheral/rtc 
 The Real Time Counter (RTC) uses the low-frequency clock source (LFCLK, 32KHz).
That means less resolution (~30us) and lower power consumption. The RTC features a 24 bit
Counter and a 12 bit prescaler. 
 When using prescaler value 0 the RTC will overflow after 512 seconds, with a period of 30us. 
With a max. prescaler value the RTC will overflow after ~582.5 hours, with a period of 125ms. 
 I don't know what SDK you are working with, so I just assume SDK 14.2.0. 
To implement such a counter in your project, I would suggest that you take a look at the
 Application Timer in the infocenter. 
The function app_timer_cnt_get() can be used to get the current value of the RTC1 counter.
Then you need to convert the number of ticks to ms. 
 Take a look at my answers in these cases, that might be of interest. 
 devzone.nordicsemi.com/.../ 
 devzone.nordicsemi.com/.../ 
 Hope that helps, but be sure to let me know if you face any problems. 
Best regards, 
Joakim