site_archiver@lists.apple.com Delivered-To: Bluetooth-dev@lists.apple.com Julian - Have you read this paper: https://www.eit.lth.se/sprapport.php?uid=945 It is pretty on-point for what you are trying to achieve. On Tue, Feb 12, 2019 at 3:26 AM Julian Vogels <julian@soundbrenner.com> wrote:

Dear list,

Thank you for interesting topics and your support in the past.

We’re building a peripheral device (Nordic nRF52840) which needs to be *time synchronized* with the central device (iOS device) once on connection. When sending a timestamp, we have unknown, noticeable latency. This is because we cannot know the time it takes until one packet is processed on the central side, sent, and then received and processed on the peripheral side. However, we do know that there are Connection Events (CEs) occurring every Connection Interval (30 ms), where the packets are exchanged. We were planning on using the CEs to infer the actual time of send/receive, as the event is happening at the same time on both sides and has a very short duration.

On the peripheral device, we are able to generate an interrupt when the CE occurs. *On the iOS device, we are unable to detect when a Connection Event is occurring*. Is there any way to get the synchronized Bluetooth clock tick (Connection Event) on iOS? Or maybe we’re on the wrong track altogether?

Any other ideas on how do you synchronize two timestamps on peripheral and central device? (We already have clock drift compensation by the way, I am just asking about timestamp sync.) Our requirement is a latency/jitter under 5-8 ms.

I hope I sparked someones interest in this engineering problem! Please send me a message if anything is unclear.

All the best,

Julian <http://www.soundbrenner.com> *Julian Vogels* CTO & Co-Founder +49 176 5659 1152 (GER) | Skype: julian.vogels | WeChat: julianvogels www.soundbrenner.com [image: LinkedIn] <https://www.linkedin.com/company/6396866> [image: Indiegogo] <http://bit.ly/soundbrennerpulse> [image: Facebook] <https://www.facebook.com/soundbrenner> [image: Twitter] <https://www.twitter.com/soundbrenner> [image: Instagram] <https://www.instagram.com/soundbrenner> Download our free standalone app "The Metronome by Soundbrenner" for iOS <https://goo.gl/BivAYK> or for Android <https://goo.gl/Ejruwi>

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