nrf9160 - Date and time

[Sirjee]

Hi Support, we are using custom hardware and the follwoing versions:

1. modem - 1.3.4

2. nrf-sdk - 1.9.0

3. Zephyr - v2.7.99

Our application is based on the gnss sample.

Our device operates on a battery, hence always have power.

What I have noticed is that the date and time in a few records have been set to zero.

In the "date_time_evt_handler", the date and time is obtained by "DATE_TIME_OBTAINED_MODEM".

If the unit is backup by battery, and there is a reset and we are unable to obtain the datetime from the MODEM, does the datetime get cleared?
Should not the last datetime still be valid, maybe some drift, but still valid.
Why does the driver clear the datetime.
Is there a way for me to prevent the driver from clearing the datetime?

Thanks

[Michal]

Hello and sorry for the delays.

I took over the case and I am looking into it.

If the unit is backup by battery, and there is a reset and we are unable to obtain the datetime from the MODEM, does the datetime get cleared?

I think so. The issue is that it the datetime should be kept in RAM, or else it would cause unnecessary wear on flash.

Is there a way for me to prevent the driver from clearing the datetime?

You could save it manually in the persistent memory, but like said before, the wear is an issue. I assume that the resets are random and not done manually/expected to happen?

Best regards,

Michal

[schnitzlein]

Hi I have similiar Question(s)

related with the nrf9161-DK Board.

How can I set the time manually for the nrf_modem ?
How can I override and pass the date_time_evt_handler to the nrf_modem which is running?

Behind is the story of syncing some devices over the air...
Or is there some hidden layer which provides it on PHY Layer over the air ?

I understand that the LFCLK is the time source for the nrf_modem.
Can I simply sync those sources ? so far I know it is not that easy, maybe a counter or I need from the local board the frequency etc. phase and must pass those information to the other boards.

Can you help here?
I can open another question, but I thouth it is related.

kind regards
Christoph

[Michal]

Hello Christoph,

Please open another ticket for this.

Best regards,

Michal