NRF9160 Modem CCLK overhead and intended design

RE: NRF9160 Modem CCLK overhead and intended design

Bjørn Kvaale — Fri, 30 Aug 2019 08:57:57 GMT

Would you mind upvoting any of the comments you thought were good? 🙂

RE: NRF9160 Modem CCLK overhead and intended design

GJSea — Fri, 30 Aug 2019 03:16:42 GMT

Thanks Bjorn, I'll make sure there is an HTTP backup to get and set the time from an NTP server if the AT+CCLK is not initially acquired.

RE: NRF9160 Modem CCLK overhead and intended design

Bjørn Kvaale — Wed, 28 Aug 2019 11:03:11 GMT

Received an update from Finland: "Modem internal clock is updated always when time is received from LTE network. If user has set time with AT+CCLK, it is overwritten. It should be noted that not all networks are sending time and date information and thus it can't be guaranteed that correct time exists in modem.

Modem FW keeps the clock also during PSM, however the most strict accuracy requirements can't be fulfilled.

The response to AT+CCLK? is generated internally in modem. No network signalling is needed."

RE: NRF9160 Modem CCLK overhead and intended design

Bjørn Kvaale — Tue, 27 Aug 2019 08:10:50 GMT

Sorry for the delayed response. The clock command should read the real time clock, not the network time. So for me, it does not really make sense why it should return the LTE network time.

I believe this could be the case, as the RTC uses the Low Frequency clock, which is only turned off during System Off mode. However, PSM mode is not system off mode, so I believe this should be fine. I will double check this internally.

Let me check internally & get back to you.