📝BLE
(Bluetooth Low Energy)
BLE advertising frame:
| Preamble | Access Address | PDU | CRC |
| 1 octet | 4 octets | 2 to 39(4.0) or 257(5.0) octets | 3 octets |
For all advertising channels, Access Address is always 0x8E89BED6.
PDU format:
| Header (16 bits) | Payload |
Header format (4.0):
| 4b PDU Type | 2b RFU | 1b TxAdd | 1b RxAdd | 6b Length | 2b RFU |
Header format (5.0):
| 4b PDU Type | 1b RFU | 1b ChSel | 1b TxAdd | 1b RxAdd | 8b Length |
| PDU type | Packet Name | comment |
|---|---|---|
| 0000 | ADV_IND | broadcast advertisement |
| 0001 | ADV_DIRECT_IND | directed advertising |
| 0010 | ADV_NONCONN_IND | beacons |
| 0011 | SCAN_REQ | for connection |
| 0100 | SCAN_RSP | for connection |
| 0101 | CONNECT_REQ | for connection |
| 0110 | ADV_SCAN_ID | additional info on scan |
Max A. recommendation:
- getting started with bluetooth low energy
- https://habr.com/ru/post/319244/
- bluetooth core specification 5.2 pdf