RE: getting millis from startup

Joakim Jakobsen — Fri, 19 Jan 2018 12:45:10 GMT

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