How to use Time-sync in nrf52840

[Yogeshwar]

I am using Nordic's nRF52840 DK board.

I wanted to sync time on End Device(nrf52840DK Board) via sending packets to it. What should I do?

what clock/rtc library or API's do I need to use to read or write to the RTC on the board.

[Yogeshwar]

I took a reference from https://github.com/NordicPlayground/nrf5-calendar-example,
but there were certain things I didn't get.

Can somebody explain to me what is meant by calibrated and uncalibrated time in this example

[Sigurd]

Yogeshwar said:

I wanted to sync time on End Device(nrf52840DK Board) via sending packets to it. What should I do?

Could you explain this some more.

1) What do you mean by sending packets to it ? Is this BLE packets?

2) What type of device is sending the packets to the nRF52840 ?

3) what data is the device sending to the nRF52840? updated clock data?

Yogeshwar said:

Can somebody explain to me what is meant by calibrated and uncalibrated time in this example

You can update the time with the function nrf_cal_set_time() several times. The second time you call the function, it will calculate the difference between the first and the second time you set. Based on this difference it will produce a "m_calibrate_factor" that is used to estimate the drift the clock had. When knowing how much the clock is drifting, we can adjust for this in the “calibrated” time.

[Yogeshwar]

• By packet here I meant Thread packets
• My thread Network gateway is sending the packets 
• Yes, the data here is updated clock data

[Sigurd]

Ok. If you want to a local clock running on your end-device, then the nrf5-calendar-example is good starting point. The nrf5-calendar-example example uses RTC0 by default, you should change this to use RTC3 when integrating it in the Thread application. Might also want to set CAL_RTC_IRQ_Priority to 6