Of what does a notification package consist? ( Packet Structure )

[muhkuhns]

I mean what kind of header information and stuff besides the data. I could only find this for advertising packets.

A graphic or list like this would be nice:

byte 0-1 // byte 2-30 // byte 31

sendername // data // crc

and a citable source :)

[endnode]

Well citable source is easy: BT SIG specification 4.0 or higher;) If you mean "Handle Value Notification ATT method" it is standard PDU, isn't it? I'll leave these few drawings here but I believe you'd like to to get access to this presentation: original presentation by BT SIG from 2010 during official introduction of LE as part of BT 4.0 (member login required but registration is for free).

Cheers Jan

PDU on LE LL layer

PDU on LE ATT layer (no authentication)

PDU on LE ATT layer (authentication signature)

Note:

"Opcode" for "Handle Value Notification" ATT method is 0x1B. "Attribute Parameters" consists of 16-bit ATT handle number and actual data.

[endnode]

Hi John, 20 bytes is available payload on top of GATT layer in case you are using default MTU size (ATT_MTU = 23 bytes, 3 bytes are GATT protocol overhead). I'm not sure how exactly NUS (Nordic's UART Service) works but with latest SoftDevice (Nordic BLE stack implementation) S132 V3.0.0 you can support larger ATT_MTU size. The topic discussed in my answer is living on lower (Link) layer and there PDU has always 37 bytes (just upper layers such as ATT can fragment and transport larger messages on top of them). The infographic in you hyperlink corresponds to first slide linked by me above. Have you seen the whole presentation I've suggested above? Do you have understanding how whole BT Smart stack works?

Cheers Jan