NCS SDK With Bluetooth Periodic Adv Demo

RE: NCS SDK With Bluetooth Periodic Adv Demo

Einar Thorsrud — Wed, 17 Aug 2022 11:42:32 GMT

Hi,

You are right, there is a timing issue here in the SoftDevice controller. The periodic advertiser sends its packet 40 us later than indicated in the SyncInfo of the AUX_ADV_IND packet. This will be fixed in a future nRF Connect SDK release.

RE: NCS SDK With Bluetooth Periodic Adv Demo

Einar Thorsrud — Wed, 17 Aug 2022 10:42:05 GMT

Thanks for confirming. We are looking into this now.

RE: NCS SDK With Bluetooth Periodic Adv Demo

Tovms zhangsan — Tue, 16 Aug 2022 07:56:27 GMT

Abs using the softdevice not Zephyr LL.

RE: NCS SDK With Bluetooth Periodic Adv Demo

Tovms zhangsan — Tue, 16 Aug 2022 07:55:37 GMT

RE: NCS SDK With Bluetooth Periodic Adv Demo

Einar Thorsrud — Tue, 16 Aug 2022 07:51:14 GMT

I see. I am not able to see this clearly right now, but I have asked our Bluetooth stack developers (including Jonathan Rico ) to look into it.

In the meantime, can you clarify which nRF Connect SDK version you are using and verify that you are really using the SoftDevice controller (and not the Zephyr LL)?

RE: NCS SDK With Bluetooth Periodic Adv Demo

Jonathan Rico — Tue, 16 Aug 2022 06:27:32 GMT

I don't see the issue either, the spec clearly says you can have offsets that are bigger than 245700us and 4.08ms is definitely lower than that. You can even have offsets measured in seconds if you set the offset adjust field to 1.

RE: NCS SDK With Bluetooth Periodic Adv Demo

Tovms zhangsan — Mon, 15 Aug 2022 12:14:28 GMT

BLUETOOTH CORE SPECIFICATION Version 5.3 | Vol 6, Part B page 2697

The actually AUX_SYNC_IND should be sent after AUX_ADV_IND syncPacketWindowOffset+[0-Offset Units]

The syncPacketWindowOffset value is the time from a reference point to the
start of the AUX_SYNC_IND packet that this SyncInfo field describes.

But, in ellisys capture, you can see ncs controller sent timestamps always bigger than spec define.

RE: NCS SDK With Bluetooth Periodic Adv Demo

Einar Thorsrud — Mon, 15 Aug 2022 12:09:28 GMT

Can you refer to where in the spec you see that?

RE: NCS SDK With Bluetooth Periodic Adv Demo

Tovms zhangsan — Mon, 15 Aug 2022 12:07:31 GMT

Hi,

you can see the second picture, which made red circle, but according spec define, not this value, should smaller than this.

RE: NCS SDK With Bluetooth Periodic Adv Demo

Einar Thorsrud — Mon, 15 Aug 2022 12:04:32 GMT

Hi,

I do not quite understand. As you have made red circle around the Sync Packet Offset, I assume you see an issue here, but I cannot see what it is. Can you elaborate? Generally, this indicate the time from the AUX_ADV_IND to the next AUD_SYNC_IND, which can be long or short and will vary from packet to packet, as those are independent.