Apple Ble Protocol Documentation wanted

[lgoette]

I think a markdown that documents Apples ble-protocol would be nice for developers.

I don't know it well enough to do it my self, but I found something about the connection state by some testing:

Already known:

• 0x00: Disconnected
• 0x04: Idle
• 0x05: Media Playing
• 0x06: Call
• 0x07: Ringing

What I found:

• 0x08: Handover to another device while Idle
• 0x09: Handover to another device while media playing
• 0x0A: Handover to another device while in call
• 0x0B: Handover to another device while ringing

I don't know why there are different states. Perhaps something with closing the audio stream correctly.

Edit: The Reason is probably that single bits hold a specific Information:

  bit:   7  6  5  4  3  2  1  0
         0  0  0  0  0  0  0  0                                                                                   
                     │  │  └──┘                                                                                   
                     │  │   └── activity: 00=idle, 01=music, 10=call, 11=ringing
                     │  └────── connected to a device                                                             
                     └───────── handoff in progress                                                               

I am using the AirPods Pro 1.

Also 0x09 is labeled "HANGING_UP" in blemanager.h. Why is that? Hanging up a call was no state in my case. Just going from 0x06 to 0x04

[kavishdevar]

There was a doc for the BLE advertisement format, but I recently removed it because I felt it needed more work, and like you mentioned about the hanging_up state (the original author of the old linux app also added this doc)- it was not entirely accurate based on my testings.

However, there are existing documentations that you can find in other projects.

[lgoette]

Do you have examples in what Projects I should have a look? I did not find good documentation on that topic.

[pabloaul]

The continuity protocol in general is documented quite well here: https://github.com/furiousMAC/continuity/

I can't quite tell which message and byte position you are specifically referring to, but the most relevant one for the AirPods can be found at messages/proximity_pairing.md in the repo above.