Chengdu Ebyte Electronic Technology Co.,Ltd. E73-TBX User Manual
Copyright ©2012–2019
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Chengdu Ebyte Electronic Technology Co.,Ltd.
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For broadcast messages, It’s fixed 0x8e89bed6. (The access address also determines the sequence of the preamble)
Header (1 byte):
The sequence is broadcasting message type (4bit), reserved bit (2bit), sending data address class (1bit), receiving address
type (1bit).
Length (1 byte):
Indicates the length of broadcast data (broadcast address AdvA + data AdvData)
Broadcast data:
The data segment we need to parse will be explained in detail later.
Check (3 bytes:):
CRC check
3.4.3.
Packet capture analysis
Access address in red is the fixed Access Address for Broadcasting 0x8e89bed6. (The packet capture software does not
convert byte order)
In the header field:
Broadcast type is universal connectable broadcast (type is 0)
The address type is public address, and both TxAdd and RxAdd are 0.
The length field indicates that the length of ADV + AdvData and the address of the broadcasting device are set by myself.
ble_gap_addr_t add={.addr_type=BLE_GAP_ADDR_TYPE_PUBLIC,
.addr={0x01,0x02,0x03,0x04,0x05,0x06}}
Because the address is 48-bit address, LSB format. So the real address is 0x060504030201. A lot of data in AdvDara is
what we need to parse. The following is the detailed information, which has the header data added by the capture
software.
Start from packet data
2C is the total bytes of packet data
D6 BE 898E is the access address (byte order problem)
00 is the header field (generic broadcast type, public address)
21 is the value of the length field, indicating the total number of bytes of ADV + AdvData
01 02 03 04 05 06 is the address of broadcasting device
Bluetooth Instruction 4.1 states that the data format is
| length | AD type | AD data|
