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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3.3.
The working status of the device and the type of Bluetooth device
BLE device has following working status:
When the BLE device does not establish a connection with any device and there is no broadcast, It’s on the ready state. If
the device is connected to the host by sending a Bluetooth broadcast from the ready state, we call it a slave. If the device
from the ready state is connected to the slave by scanning the broadcast of the Bluetooth peripheral, we call it the host.
3.4.
Analysis of Bluetooth Broadcasting
3.4.1.
Preface
The message is composed of data bytes and is transmitted in bits, which inevitably involves byte order issue. For each
byte transmission, it always starts at the lowest bit. For example, 0x80 is sent as 00000001,0x01 is sent as 10000000. At
the same time, most byte fields are sent from low bytes. The sending sequence of 0x010203 is110000000-
100000010000000. Since the packet capture software may not fully know which data is sent from the low byte, some of
the captured broadcast data may need to be read backwards in bytes.
3.4.2.
BLE Broadcast Data Structure
In the link layer, BLE broadcast messages are divided into the following parts:
| Leader | Access Address | Header | Length | Broadcast Data | Check|
The general package grabbing tool will display segment after grabbing broadcast data. This paper mainly analyses the
content of broadcast data segment.
Leader (1 byte):
It’s used to configure the receiver's automatic gain control.
Access address (4 bytes):
