Nrf9160 RTC specs anywhere?

[rkguy]

I haven't been able to find documentation for the RTC or RTCs on the 9160. I want to know what the drift is and which RTC timers are available in various stages of sleep when using something like edrx or psm

[Joakim Jakobsen]

Hi.

You can find the documentation on our website https://www.nordicsemi.com/DocLib

I believe the documentation you are looking for is;
nRF9160 OPS - RTC - Real Time Counter
NRF9160 OPS - Clock Management

Let me know if there is anything else you are looking for.

Best regards,
Joakim

[rkguy]

Thank you. While this answers the original question, do you have an opinion on whether it is more worthwhile to try to implement a date time clock using RTC counters or just get an external rtc clock? Specifically, while I like less components I am wondering if keeping a timestamp calendar using just the 9160 will severely impact battery life? 

Here are relevant links

https://github.com/NordicPlayground/nrf5-calendar-example

And an older one

https://devzone.nordicsemi.com/f/nordic-q-a/2107/nrf51822-long-time-timekeeping

The other concern is how hard it would be to port this logic to work with Zephyr. 

Looking for informed opinions

[Cyril]

Hello,
I think you can rely on having the MCU draws about 3uA while keeping the calendar active. 
https://www.nordicsemi.com/DocLib/Content/Product_Spec/nRF9160/latest/_tmp/alta-nRF9160/autodita/CURRENT/parameters-id_current_sleep

I never used Zephyr, but looking at the documentation, you can configure Zephyr to several power modes: https://developer.nordicsemi.com/nRF_Connect_SDK/doc/latest/zephyr/subsystems/power_management.html

You should try that example and measure current: https://developer.nordicsemi.com/nRF_Connect_SDK/doc/latest/zephyr/samples/subsys/power/power_mgr/README.html

To my mind, there is no need for an external RTC.

Best