Nordic Clock Drift with Internal LFCLK when trying to synchronize with an external client or another Nordic clock (Nordic -nRF52840)

[Akhil Bhargav Josyabhatla]

Hello,

I am using a nRF52840 with SDK 14.2 and I am trying to synchronize my "app timer" which uses the RTC1 with respect to an external client which is connected over TCP protocol.

Hardware Setup: nRF52840 is connected to a Wi-FI module over UART and the TCP connection is established between the Wi-Fi module(Server) and a client program on a PC.

I send a command to the Nordic from client to start the timer, also start a timer at the same time on the client.
When I receive a packet(with the timestamp in mS) at the client side, I compare the timestamps of Nordic and MAC client and expect the difference= (time_at_client - time_from_nordic) to be positive but it's negative and grows very large every second.
I am assuming it's because of the clock drift on the nRF52840. I want to solve this issue as I want to synchronize time between nRF52840 - Client and also synchronize between 2 nRF52840 modules eventually.

Anyone faced this issue before and know of any software solution?

Thanks in advance,
Akhil

Notes:
1) Tried comparing TICKS and converted mS. See this issue with both values.
2) All calculations are taken care of.
3) I understand that external Crystal could increase accuracy and help in this scenario but there's a hardware limitation.

[Cecylia]

Hi Haakon, thanks for the reply!  So, based on your inputs, and after much experiments, we decided to sync the whole system time from another Nordic which has an external clock. This shows much better results :)

[haakonsh]

Glad to hear^^