SNVS_HP RTC and SNVS_LP SRTC

[jeffthompson]

Is there a user guide for the RTC and SRTC features available through SNVS_HP and SNVS_LP? I'm confused because the MCUXpresso SDK API Reference says

there is no way to access the SNVS_LP registers except through the SNVS_HP

and ConfigTools Peripherals only allows configuration of SNVS_HP. However, the same document lists both SNVS_HP_RTC_SetDateTime/SNVS_HP_RTC_GetDateTime and SNVS_LP_SRTC_SetDateTime/SNVS_LP_SRTC_GetDateTime functions. Since SNVS_LP is always powered up, why does it even hand an Init function? Can I use SNVS_LP exclusively? When should I use SNVS_HP? I appreciate the flexibility, but some guidance is needed, and the SDK API Reference doesn't offer any. I have looked at the example code it illiustrates setting the SRTC and reading the RTC. If all I need is the ability to occasionally get a timestamp and set the time from a time server, is that I need to do?

[enricorocheti_]

I still don't understand the real difference between using SNVS_HP_RTC and the SNVS_LP_SRTC, the doccumentaion of the MCUXpresso SDK isn't clear and the reference manual (i.MX RT1160) neither.

I want to use the clock that will be backed-up by a coin cell battery, so can I use just the SNVS_LP_SRTC (because its date will remain stored on the SNVS_LP registers)? Or is it mandatory to use the SNVS_HP_RTC and sync it up with the SNVS_LP_RTC after power up? 

[jingpan]

Hi Jeff,

The SNVS_HP provides an interface between SNVS_LP and the rest of the system. Without SNVS_HP, SNVS_LP can't be touched.

If the uninterrupt power is lost or when LP power is connected to HP/main chip power and dispense with a coin cell battery, SNVS_LP need to be initialized.

Regards,

Jing