Profile of Bluetooth

A very important feature of Bluetooth is that all Bluetooth products do not need to implement all Bluetooth specifications. To make it easier to maintain compatibility between bluetooth devices, the profile is defined in the Bluetooth specification. Profile defines how a device implements a connection or application. You can understand profile as a connection layer or application layer protocol.
For example, if a company wants their Bluetooth chip to support all Bluetooth headsets, it only needs to support headset profile without considering the communication and compatibility between the chip and other Bluetooth devices. If you want to buy a Bluetooth Product, You should know which profiles are required for your application and make sure that your Bluetooth Product supports these profiles.
Four of all profiles are basic ones, which will be used by other profiles. They are:
Gap profile: Generic Access Profile, which ensures that different Bluetooth products can discover each other and establish a connection.
Sdap profile: service discovery application profile through which a bluetooth device can find services provided by other Bluetooth devices and query related information.
SPP Profile: Serial Port profile, simulating serial communication
Goep profile: Generic Object Exchange profile, Common Object Exchange. The profile name is confusing. It defines data transmission, including synchronization, file transmission, or pushing other data. You can understand it as a content-independent transport layer protocol, which can be used by any application to transmit Custom Data Objects.
In addition, Bluetooth also defines nine application (usage) profiles.
CTP profile: Cordless Telephone profile, cordless phone.
IP profile: intercom profile, which establishes a voice connection between two devices. In other words, it turns two expensive Bluetooth devices into inexpensive walkie talkie devices.
HS profile: headset profile, used to connect the headset.
DNP profile: dial-up networking profile, used to provide the dial-up network function for the PC.
FP profile: Fax profile, fax function.
Lap profile: LAN Access Profile, which uses the PPP protocol to establish a LAN.
OPP profile: Object push profile, used to transmit data objects between devices.
FTP profile: File Transfer profile, used for file transfer.
SP profile: Synchronization Profile, used for synchronization between different Bluetooth devices to maintain data consistency.
The profile problem of Bluetooth is quite complex. These profile specifications occupy 400 pages of content in all Bluetooth specifications.

Bluetooth is a short-distance wireless communication and transmission interface, which allows the transmission distance from 10 meters to 100 meters, when a mobile phone or computer containing Bluetooth is in multiple environments with Bluetooth devices, the device enters the STANDBY state before being added to the Bluetooth micro-network. In this status, it will listen to call messages at any time until the received signal is related to its own identification code, it will activate the Bluetooth service called Master, start searching for all peripheral Bluetooth devices called slave and call the link Program . Next, confirm the identification code and synchronize the signal time to determine the sequence of the Next Hop Frequency. These devices are connected into a group called the microgrid piconet. A micro-network can be formed by Bluetooth to share information. seven to eight active service providers, active slave device and 255 waiting service provider standby slave device, can be provided. To maintain information transmission, one of the devices in the micro-network is the main control device of the micro-network, while other devices are subordinate devices. Any device in the micro-network can be a master device, but there is only one master device in the micro-network at any time. Bluetooth provides point-to-point or point-to-point connections. Master is responsible for establishing connections between bluetooth devices. In a single region, multiple micro-networks can be added, this multi-network architecture is called Stack scatternet.
The basic communication hardware mechanism can be used for point-to-point transmission, So network communication can provide convenient and high-level application interface software. Most of the software processes low-level communication projects and automated programs. It can be easily applied to communications, and most applications rely on network software to come online. When transmitting data, a consistent specification must be obtained for complex communications. This specification is called protocol. The above mentioned Bluetooth-related protocols are described in detail here:
A. On the physical layer physical, the LMP link manager protocol is used to control online control between different components, Link Status of components, encryption and decryption of transmission packets, and identity authentication.
B. The host controller interface is used to define the control commands for interfaces connecting Bluetooth and host devices.
C. L2CAP Logical Link Control and adaptation protocol, which is used to connect the software interfaces of different upper-layer applications to different applications. In addition, services such as multiplexing, quality of service quality, segmentation of packet cutting, and reassembly integration are also provided. The information packets transmitted from the upper layer are organized into 64 KB.
D. rfcomm rf communication protocol, which provides the function of serial connection, similar to RS232 control signals and data transmission signals.
E. TCS telephony control service protocol, which is a binary TCS bin. It is responsible for establishing and controlling call control and mobile roaming management mobility management for online telephone signals. In addition, the AT command is used to enable the mobile phone or computer to access the Internet through a hardware interface connected to Bluetooth. At this time, a fax command is also provided.
F. SDP Service discol protocol, which contains service records, mainly records service features and identity authentication. In addition, it describes what needs to be done after service discovery. It mainly establishes a call online and uses the call protocol.
The G. Profiles API layer provides different modules for audio, data, and control. Currently, there are four types and thirteen types of protocols.
H. application provides communication protocol functions and application interfaces required by Application Software Based on application requirements such as voice, data, and control.
Address: http://blog.csdn.net/linweig/archive/2010/05/31/5637674.aspx