Introduction to Bluetooth headset and headfree

Bluetooth headset function, that isBluetooth
Headset/headfree profile,Implementation is more complicated than imagined. Earlier Bluetooth specifications only defined the profile of headset,
The implementation principle of headset is to extend an interface on the HCI Layer to transmit SCO connection-oriented synchronized audio data packets. The audio stream must be a single-channel 8 K audio-level PCM. With the development of the demand, it is obviously unable to meet, so we have added the a2dp protocol. The a2dp protocol is on The L2CAP layer and uses SBC to compress and use ACL asynchronous data packet transmission, which can support CD-level audio streams.

In handset mode, when a mobile phone is in normal mode, the receiver is near the ear to answer the phone. The handfree mode is different. For example, you can use the headset mode to answer a call.