clock sync using periodic advertising

[Dor Sadeh]

I want to sync the clocks of 2 BLE devices as accurate as possible.

My thought was to use periodic advertising, because the radio opening window is 30[usec] so this accuracy is very good for my needs.

Now I only need to call k_uptime_get() just before radio transmission. What would you say is the best way to do it?

If there are any other options for syncing clocks using radio please share.

[Hieu]

Hi Dor Sadeh,

You can use Radio Notification callback to get a callback when the RADIO peripheral is started or stopped. It seems this feature is new and hasn't been included in an official SDK release yet, however.

You could also use PPI to connect a GPIO output event to a relevant RADIO event, and then connect the GPIO output to a GPIO input for an interrupt.

Bluetooth: ISO time synchronization (nordicsemi.com) is also a solution for time sync.

Finally, there is also a proprietary time sync solution from Nordic, but this also seems not released yet. It is demonstrated here: Bluetooth: Connection time synchronization (nordicsemi.com).

Hieu