Datetime/RTC example

Hi,

I believe zephyr logging API supports setting an actual timestamp:

https://github.com/zephyrproject-rtos/zephyr/blob/06ab394f05c0d7561a815cbaf4e7131fe91510f1/include/logging/log_ctrl.h#L65

You could get the time via GPS, or NTP, then set it via this function.

Kind regards,

Håkon

My question relates more to the actual getting of the current time. I can read the RTC off of the modem using "AT+CCLK?" but this time is not accurate until I set it with "AT+CCLK=___". For example, right now when I read the time with AT+CCLK, it is 5 hours ahead. What are my options for getting the current time so I can set it in the modem and use it throughout? Of these, what would be the most reliable?

I'm thinking that on boot, I would want to request the current time and then save it in the modem. What is the most reliable way of doing this?

jlangballeswift said:

My question relates more to the actual getting of the current time. I can read the RTC off of the modem using "AT+CCLK?" but this time is not accurate until I set it with "AT+CCLK=___". For example, right now when I read the time with AT+CCLK, it is 5 hours ahead. What are my options for getting the current time so I can set it in the modem and use it throughout? Of these, what would be the most reliable?

 It is given with a offset at the end, as per the AT specification here:

https://infocenter.nordicsemi.com/topic/ref_at_commands/REF/at_commands/mob_termination_ctrl_status/cclk_read.html?cp=2_1_3_28_1

You can override this by setting it back with your time + timezone.

jlangballeswift said:

I'm thinking that on boot, I would want to request the current time and then save it in the modem. What is the most reliable way of doing this?

You have several ways, as mentioned; ntp and gps. You can also query the lte network for time, and use AT+CCLK.

Kind regards,

Håkon

Hi Hakon,

Maybe this is a separate issue but even when accounting for the timezone difference from CCLK, it is still inaccurate unless it has been set properly. I expected it to automatically get the correct time from the cellular network but it looks like it doesn't do that.

What I ended up doing is using this sample to get the time using NTP, which I then use to set the modem RTC with AT+CCLK=___. Then I was able to get accurate timestamps from the AT+CCLK? command.

Hi Hakon,

Maybe this is a separate issue but even when accounting for the timezone difference from CCLK, it is still inaccurate unless it has been set properly. I expected it to automatically get the correct time from the cellular network but it looks like it doesn't do that.

What I ended up doing is using this sample to get the time using NTP, which I then use to set the modem RTC with AT+CCLK=___. Then I was able to get accurate timestamps from the AT+CCLK? command.

Hi,

I had been following your post and needed a bit of help to get things going for me.

I was looking at this example and wanted to know how did you link the NTP time to the AT+CCLK command to get the real time instead of manually entering the AT+CCLK command.

Also, the NTP sample does not run in my SES (NCS v1.3.0) :(

Thanks