DATA FORMAT
The Link Layer has only one packet format used for both advertising channel
packets and data channel packets
链接层不管广播通道还是数据通道,都公用一种包格式
参数:
1.Preamble
2.Access Address
![](http://img.e-com-net.com/image/info8/7504b1fcf1c048058404ef765aec3b3a.jpg)
![](http://img.e-com-net.com/image/info8/613b0b790298469fa755c229c6937a33.png)
3.PDU
PDU分两种,一种是广播信道的PDU,一种是DATA信道的PDU
1)广播信道PDU:
![](http://img.e-com-net.com/image/info8/42fd36a5526f4b478b23377bb6d2f944.jpg)
![](http://img.e-com-net.com/image/info8/d89184e7adf14070a02954c8c97a8ef4.png)
![](http://img.e-com-net.com/image/info8/e9930097d5d04eac89bc685e4a486d7f.jpg)
2)DATA信道PDU
![](http://img.e-com-net.com/image/info8/b08078e1790a470bb053de0ecd1b8228.png)
![](http://img.e-com-net.com/image/info8/935b8b03fb284dad89333dd741ffe472.png)
![](http://img.e-com-net.com/image/info8/67975327650d4c34a4cf464e295d1d20.jpg)
DATA PDU也分两种PDU(正常data PDU,control data PDU)
正常data PDU(用于L2CAP传输数据)和control data PDU( is used to control the Link Layer connection)通过以下图区分
control data PDU 图示:
opcode:
![](http://img.e-com-net.com/image/info8/9927620be6d74fe8ba2196eadfb32b7d.jpg)
![](http://img.e-com-net.com/image/info8/3908fee2a9524a40aba88e55311f937d.jpg)
4.CRC
At the end of every LinkLayer packet there is a 24-bit CRC. It shall be calculated over the PDU