Datetime/RTC example

[jlangballeswift]

Hi,

Are there any examples utilizing the nRF9160 RTC? I want to timestamp my data that I send to the cloud because my use-case involves queuing up data for extended periods of time (a few hours) and then sending it all at once. It would be nice if I could timestamp the data with actual timestamps instead of just milliseconds since boot. What are my options for this?

Thanks

[Håkon Alseth]

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

[jlangballeswift]

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?

[Håkon Alseth]

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

[jlangballeswift]

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.

[Adeel]

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