Summary:
Now many devices support Bluetooth, and the mobile phones are no exception. So what applications can Bluetooth implement, and what Bluetooth protocols will be used in these applications?
1. A2DP protocol, enables headphones or audio devices to connect through Bluetooth to listen to music:
A2DP full name is Advanced Audio Distribution Profile Bluetooth audio transmission model protocol. The A2DP protocol can use the chip in the headset to stack the data to achieve the purpose of high definition transmission of sound.
However, the headphones that do not support A2DP are Bluetooth stereo headphones, the basic requirements of stereo implementation are double channels, so monophonic Bluetooth headphones cannot achieve stereo.
Whether Bluetooth headphones or sound supports the A2DP protocol depends on whether Bluetooth product manufacturers use this technology.
2. HFP protocol, so that Bluetooth devices can control the phone:
HFP is short for Hands-free Profile, allowing Bluetooth devices to control the phone, such as answering, hanging up, rejection, voice dialing, etc. Rejection and voice dialing depend on Bluetooth headset and mobile phone support.
Bluetooth can control the phone, such as answering, hanging up, rejection, voice dialing and so on, rejection, voice dialing.
The HFP protocol defines two components: audio gateway (AG), and hands-free component (HF).
Audio gateway (AG): the device is an input / output gateway for audio (especially mobile phones).
Hands-free component (HF): the device acts as a remote audio input / output mechanism for audio gateways and can provide a number of remote control functions.
All in all, this protocol is the protocol that must be used when using Bluetooth to answer the phone. Therefore, in order to achieve Bluetooth headphones to answer the phone, mobile phones and Bluetooth headphones must also support the protocol.
3. PBAP protocol, phone book access specification:
PBAP protocol user Bluetooth device reads the contents of the mobile phone address book (phone book), which is generally used in the import and export of vehicle Bluetooth or mobile phone address book.
Vehicle Bluetooth is in the process of driving, you can map the phone book to the car screen, through which you can directly operate to find contacts and make calls.
To implement this function, the PBAP protocol need to be used, which defines the protocols and programs that can be used to retrieve phone book objects between different devices.
One device (client) can browse and download the phone book of the other device (server), but the phone book of the other end (server) is not allowed to be changed.
The realization process is the client-server process, the client requests the connection, and the server side authorization can access and download the server phone book normally.
4. AVRCP (audio / video remote control specification)
AVRCP is used to send commands (such as forward jump, pause, and play) from the controller (such as stereo headphones) to the target device, such as a computer with MediaPlayer)
5. HSP
Describes how Bluetooth headphones communicate with computers or other Bluetooth devices, such as mobile phones. Once connected and configured, headphones can be used as audio input and output interfaces for remote devices. This is the most commonly used configuration for current popular Bluetooth headphones and mobile phone. It relies on 64 kilobits encoded audio / s CVSD or PCM and AT commands from a subset of GSM 07.07, including minimal power control, answering calls, hanging up, and volume adjustment. A typical usage scenario is to use wireless headphones to connect to a mobile phone. Several device types of HSP may be used: headphones, mobile phones, PDA, personal computers, laptops, and provide the basic functions required to communicate between mobile phones (mobile phones) and headphones. The
6.OPP (Object Push Profile)
Bluetooth communication program part needs to use the data object OPP Profile: Object Push Profile for data transmission between devices because OPP profile is subdivided into OPPC (client) side and OPPS (server) terminal profile. The difference between the two profiles is that only the client side can initiate the data transmission process, but in the case of communication between the attachment device and the mobile phone, the existing mobile phone also has the need to initiate the transmission request from the device side. So you need to implement both OPPC and OPPS profile in the device.
The above Bluetooth protocols are supported in Xiaomi mobile phones.