4 ms·
You get 37 bytes, and an optional extra 37 bytes with a more complex negotiation.
by iudqnolq 5y ago
You get 37 bytes, and an optional extra 37 bytes with a more complex negotiation.
- SV_BubbleTime 5y agoMy memory is a little fuzzy, but iirc after required tags in the advertising packet you had ~28 bytes that could be tagged 0xFF - mfg data. Then there is also BLE5 which adds advertising extensions to get to 240-250bytes. And the scan response packet which was under 30 all the time. But I could be wrong about all of that, been a little while since I was that deep in BLE. Point for me is that Apple absolutely could do supply chain verification but… for some reason don’t?
- iudqnolq 5y agoI've read a bunch of different numbers around 30, but I've never used beacons personally. I pulled out my copy of the O'Reilly book on BLE (covers up to Bluetooth 4.1), which says this > Each advertising packet can carry up to 31 bytes of advertising data payload, along with the basic header information (including Bluetooth device address). I didn't know about advertising extensions, thanks for the info. Without that I'm not sure if supply chain verification is feasible? I also wonder if there's a significant battery impact to broadcasting more data. I suppose they could overload the device address uuid?
- SV_BubbleTime 5y ago4.1 is before packet extensions, but that shouldn’t matter here. The reason you’ll see different numbers is that not everyone considers the overhead the same. Some count it, some don’t. I do because it just isn’t usable.