2.Feature和ProcedureHFP必须支持下表列出的一些Feature:
这些feature通过一些procedure来实现,比如1中的connection management包括Service LevelConnection establishment和Service L evel Connectionrelease这两个procedure。其余可以参考HFP的Spec。HFP支持的Codec如下表:
![蓝牙的HFP协议笔记 hfp协议](http://img.aihuau.com/images/01111101/01080343t01f16198a00a23ed80.png)
对应的Link如下所示:
3.HFP的一些procedure(1)Service Level Connection Establishment首先必须建立RFCOMM connection,然后开始Service Level ConnectionInitialization,流程如下:
(2)Service Level Connection Release
(3)Transfer of Registration Status
Transfer of Signal Strength Indication:
其余还有很多,如Transfer of Battery Level Indication of AG,Query OperatorSelection,Report Extended Audio Gateway Error ResultsCode等可以参考HFP的Spec。
附:两种audio的codecCVSD: pcm: 8kHz, 16 bits, 1 channel. compression ratio: 16(controller encoding) insert ratio: 8 pcm data rate= 16kB/s =8K*16/8 CVSD data rate=8kB/s =16kB/s*8/16 air data:CVSDmSBC: pcm 16kHz, 16 bits, 1 channel. compression ratio: 4 (hostencoding: 240->60) pcm data rate= 32kB/s mSBC data rate=8kB/s = 32kB/s / 4 air data:transparent data (mSBC)