Bluetooth technology is one of the most widely used technologies. With Bluetooth technology, we can realize data transmission and other functions. In order to improve your understanding of Bluetooth, RenhotecIC will introduce the process of Bluetooth pairing and connection and the development of Bluetooth. If you are interested in Bluetooth-related content, keep reading.


　　Bluetooth pairing process, connection building process

　　Bluetooth is a complex process, even if there is a considerable amount of work and use experience, if not carefully understand or understand incomplete.

　　Usually we use Bluetooth headphones to listen to music, share files with different devices, call, etc., there is a pairing-connection-transfer process.

　　Bluetooth pairing process, in fact, is a certification process.

　　Why can't you connect without pairing?

　　Any wireless communication technology has the possibility of being monitored and cracked. In order to ensure the security of Bluetooth communication, Bluetooth SIG uses authentication to interact with data. At the same time, in order to ensure the convenience of use, the first communication authentication between the two Bluetooth devices is completed in the form of pairing. After pairing, the subsequent communication connection does not have to be confirmed every time. So the generation of authentication code starts from pairing, after pairing, the link key between devices is established by PIN code to generate the initial authentication code for the subsequent connection.

　　Because many personal devices do not have a man-machine interface, so PIN codes are fixed and mostly set to universal 0000 or 1234, so it is easy to guess and then establish pairing and connection.

　　Bluetooth connection

　　The current Bluetooth chip supplier provides a strong technical support capability with complete hardware and software solutions. For applications, firmware is provided to implement the underlying protocol stack, profile library and source code are provided to standardize various applications, developers can only focus on application development. Some things at the bottom of Bluetooth are often not well understood. I used to do the same, recently doing an automatic search to achieve automatic connection applications, found that there is still a need to understand some of the underlying mechanisms.

　　We can easily operate to establish a connection between a mobile phone and a hands-free device, so how does this connection work?

　　First, (master,) Main equipment That is, the device that initiates the connection will paging (page) from the device (slave, receiving connected devices), master'll be paging slave, by hopping slave scan (scan) external paging at fixed intervals, page scan, Response to response page, when scan to external A link connection will be established between the two devices, i.e. ACL link connection. After ACL link connection is established, A primary device initiates a channel connection request, A L2CAP connection, After L2CAP connection, A primary device uses a SDP to query the slave device's hands-free service, And get rfcomm access numbers, The main device then initiates a rfcomm connection request to establish a rfcomm connection. Then the connection of the application is established.


　　Development of Bluetooth

　　Bluetooth has many supporters, from the Bluetooth Special interest Group (SIG), originally launched by only five companies, to nearly 3000 business members. According to the plan, Bluetooth went through three stages from the laboratory to the market：

　　The stage is that Bluetooth products are used as accessories in high-end products with greater mobility. For example, mobile phone headphones, laptop card or PC card, or for special requirements or special occasions, such occasions only require performance and function, but not very sensitive to price, this stage is about the end of 2001 to the end of 2002.

　　The second stage is Bluetooth products embedded in high-grade products, such as PDA、 mobile phones, PC、 laptops and so on. The price of Bluetooth will fall further, the estimated chip price is about $10, and the related testing and certification work will be preliminarily improved. For the period 2002~2005.

　　After 2005, Bluetooth entered household appliances, digital cameras and other electronic products, Bluetooth network everywhere, Bluetooth applications began to popularize, Bluetooth products priced between $2~$5, each person may have 2-3 Bluetooth products.

　　At present, the marketization of Bluetooth products is in the second stage of the initial period. Bluetooth is expected to have more than 1 billion wireless users by the end of 2006, including more than 500 million users using wireless Internet access services. The third generation of mobile communication technology will provide a larger market for Bluetooth interconnection, which allows mobile phones, portable devices, personal computers, laptops and third-party access devices to connect to each other. Bluetooth modules will be installed from less than 1 million in 2001 to 1.6 billion in 2006.


　　The main market of Bluetooth technology will be low-end wireless networking, providing simple and convenient wireless networking technology is the original intention of the industry to develop Bluetooth standards.

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