BLE Mesh Time Synchronization

RE: BLE Mesh Time Synchronization

mdh — Fri, 16 Jul 2021 17:36:25 GMT

N.B. If someone comes looking for the link to the blog post that Bjorn posted, it's here now.

RE: BLE Mesh Time Synchronization

bjorn-spockeli — Thu, 25 Oct 2018 08:26:58 GMT

Hi Kenji,

both the nRF SDK for Bluetooth Mesh and the Time Sync functionality uses the SoftDevice Timeslot API, so it should be possible to add the Time Sync functionality to Bluetooth Mesh devices. However, we do not have any examples covering this and we have not verified it.

Best regards

Bjørn

RE: BLE Mesh Time Synchronization

kenjiume — Wed, 24 Oct 2018 06:57:21 GMT

Hi,

I read that blog post and confirmed that the sample project in github(nRF5-ble-timesync-demo) worked fine with two nRF52DK boards. After that, I merged the project with the light switch example in mesh SDK(v2.2.0).

Unfortunately, nrf_stack_init() calls timeslot_start() function and sd_radio_session_open() in it returns NRF_ERROR_BUSY. (called the same function in ts_enable() in time_sync.c before)

So, Is it possible to coexist meshSDK with the time synch functionality written in the blog post?

Regards,

Kenji

RE: BLE Mesh Time Synchronization

bjorn-spockeli — Fri, 04 May 2018 13:11:45 GMT

Henry: There appears to be a misunderstanding related to this global clock feature, I can at least not find it in any roadmap. Hence,I doubt that this feature was in the roadmap at all and this is not a feature we currently plan on implementing. As for your question if it is possible to synchronize devices within 1ms, the answer is yes. Please take a look at this blog post.

Best regards

Bjørn

RE: BLE Mesh Time Synchronization

Henry — Thu, 03 May 2018 11:30:51 GMT

Is there any update on the issue?
Also, I want to ask whether it is possible to sync time with error < 1ms with BLE.

RE: BLE Mesh Time Synchronization

ketil — Wed, 06 Dec 2017 12:05:21 GMT

Hi,

We do not have a global clock implemented but it is on the roadmap.

You can implement the time synchronization the way you suggest. Be aware that the clock will drift and you should set a new global time with some regular interval depending on the desired accuracy. The drift of the 32MHz crystal is typically 20ppm.

We recommend that you only broadcast your time to the closest neighbours as relaying the time can lead to lost accuracy.

Ketil