BLE Extended Advertising

[bojan]

Hello, guys!

I have a few questions about BLE extended advertising on devices running Zephyr RTOS.

First of all,  I found a periodic_adv sample under zephyr/samples/bluetooth which seems to be a good example of BLE extended advertising in action. Is there any appropriate sample for the central device that will show us how to detect and extract the data of the extended advertising?

To the best of my understanding, extended advertising consists of multiple Advertising Sets (0x01 - 0xEF). For each advertising set, we can define the data that will be advertised. Also, for each advertising set, there is a possibility to additionally exchange the data with the Scan Request/Scan Response mechanism. Is my understanding correct?

What is the size of data we can transfer in every Advertising Set? Is it the same as in an ordinary advertising packet?

In general, can we use extended BLE advertising to transfer data in multiple packets (advertising sets) without establishing a BLE connection?

Thanks in advance. Looking forward to hearing from you.

Sincerely,
Bojan.

[Simonr]

Hi

You can use the  samples/bluetooth/periodic_sync in the Zephyr tree that will scan and establish a periodic advertising synchronization to the periodic advertiser sample.

Your understanding seems correct. I think this NovelBits blog post can explain periodic advertisement and its specs better than me. Extended advertising and periodic advertising are mutually exclusive, so you can only do 31 byte advertising packets AFAIK.

Best regards,

Simon

[bojan]

Thanks for the info,  Simon.

Can we use nRF52840 Dongle and nRF Connect for Desktop BLE app to detect those Extended Advertising Packets?

Would it be also possible to do it with some of the Nordic's mobile apps (nRF Connect for Mobile, nRF Toolbox...)?

[Simonr]

Hi Bojan

No. the nRF Connect for Desktop BLE app firmware is based on an older BLE version I'm afraid, so it does not support periodic advertising packets.

The nRF Connect for Mobile app will support periodic advertising packets if the phone does so, but I believe most phones these days don't support it yet. Extended advertising packets should be visible though. We have only tested the periodic advertising using two DKs on our end.

Best regards,

Simon

[bojan]

Thanks, Simon.

I tried with the nRF Connect for Mobile app on the iPhone 11 but it seems I can't see any device that is sending extended advertising packets.

Which sample can I use and download to nRF52840DK that will help me detect the Extended Advertising packets?

Regards,
Bojan.

[Simonr]

Hi

We're still talking about the periodic advertisement application on the advertiser side, correct? If so I'd recommend the periodic_sync sample that can establish a periodic advertising synchronization to the periodic advertiser and detect periodic advertisements.

Best regards,

Simon