蓝牙4.0协议关于广播地址的说明

Hi Andi G.,

Luckily all that is explained in BT SIG specification. E.g. in v4.2 spec see Volume 6 (Low Energy) Part B (Link Layer) section 1.3 (Device Address) and Volume 3 (Host) Part C (GAP) section 10.8 (Random Device Address). If you want to stick with other spec version you will find similar chapter there.

If we want to be precise we should talk about Address (MAC) field on 3 layers of BT LE:

• Link Layer (simple 48-bit field + 2 TxAdd/RxAdd fields in PDU header - see BT SIG specification v4.2 Volume 6 (Low Energy) Part B (Link Layer) section 2.3 (Advertising Channel PDU))
• Security Manager (providing way how to resolve Private address to Publicly known within installation base)
• Generic Access Profile (clarifying how each type is tight to device role)

To make it faster I leave here screenshot from official BT SIG BLE training slides, it should be evident what options are for 48-bit MAC address coding in BLE (note that BLE is using little endian so right-most bytes and bits are in fact most significant aka MSB;)

BT LE Link Layer:

BT LE Security Manager:

BT LE Geneeric Access Profile: