Low level clock

RE: Low level clock

CheMax — Sat, 13 Jan 2018 07:06:41 GMT

Many thanks, I will definitely read and try to understand.

RE: Low level clock

Hung Bui — Fri, 12 Jan 2018 12:44:06 GMT

In addition to what endnode already explained, another issue is that if a packet is missing it will be re-transmitted and it will mess up with time synchronization.

I would suggest you to use extra channel to do time synchronization, either by an advertising packet or by proprietary protocol such as ESB. To have full control of the timing when sending the advertising packet, you should use timeslot API.

Using ESB concurrently with BLE for time synchronization is explained here.

RE: Low level clock

endnode — Thu, 11 Jan 2018 12:55:32 GMT

HCI is not supported by Nordic stack and all upper layers have no concept of time, just asynchronous calls and events. You can still do it over L2CAP or GATT with some custom protocol but due to stack processing and delay between radio interrupt on LL and event callback to your FW there is limit how precise the time synchronization could be (statistically). I would say safely below 10ms, probably even somewhere around 1-2ms. Good for most of usual "clocks" for humans but probably not enough for any precise measurements and automated applications.