Zephyr & RTC

[Сергей]

 We are evaluating nRF9160 and need to implement periodic activities

that happen on RTC interrupts. It seems like Zephyr interferes with

normal RTC usage, so my questions are:

 

1. Which RTC is reserved by Zephyr?

 

2. If there is an RTC available for user app, does Zephyr still

intercept its interrupts?

 

3. Zephyr RTC driver looks incomplete (zephyr/include/rtc.h) It

contains deprecated calls and defines based upon CONFIG_RTC_PRESCALER

which is never set. Should I look for working driver elsewhere?

 

Any advice on implementation of periodic wakeups from WFI in System ON

low power are very much appreciated.

 

 

TIA

 

Ed

[Håkon Alseth]

Hi,

 

1. RTC1 is used by the kernel: https://github.com/NordicPlayground/fw-nrfconnect-zephyr/blob/master/drivers/timer/nrf_rtc_timer.c#L16

2. Yes, the peripheral RTC0 can be used by the application: https://infocenter.nordicsemi.com/topic/ps_nrf9160/rtc.html?cp=2_0_0_5_10_9#topic

3. See this example on how to use nrfx_rtc directly: https://github.com/Rallare/fw-nrfconnect-nrf/tree/nrf9160_samples/samples/nrf9160/nrfx/rtc

 

Kind regards,

Håkon

[EdP]

Håkon,

 Thanks for your reply. I tried to follow the NRFX example but it fails to compile. It complains about NRFX_RTC0_INST_IDX which in my case is not defined. I did my homework and figured out that instantiation depends on CONFIG_NRFX_RTC symbols.

 And here is where I'm stuck because I can't find a valid place where to define these parameters. menuconfig shows them in red. Kconfig is ignored. So, where should I define these symbols provided that my setup is Unix Makefiles, not SEGGER?

[Håkon Alseth]

Hi Ed,

 

This should be fixed in master now, where you can select the specific NRFX component you'd want to use.

However, when using an older codebase than master, you need to do this:

https://github.com/Rallare/fw-nrfconnect-nrf/blob/nrf9160_samples/samples/nrf9160/nrfx/rtc/prj.conf#L11

Kind regards,

Håkon