The Bluetooth Hands-Free GSM-Based Communication System

In recent years, with the rapid development of science and technology, continuous improvement in people’s living standards, the national economy has developed well. The broader market of cars attracts a large number of trader and customers’interesting. Safety, comfort, easy operation, maturity of function has become an important selection for users. In-vehicle communications systems are installed by most car manufacturers at the factory at home and abroad and few self-configurations. The systems are single, expensive function, or operate complexly, use inconveniently.In this paper, research and development of a practical Bluetooth hands-free communications systems are researched and developed based on the existing GSM technology. The system not only has the general mobile phone voice communication, but also has a remote control, automatic alarm functions because of the use of GSM chips. The terminal of Bluetooth hands-free communications is easy operation, practical function, outstanding advantages compared to other mobile terminals. Firstly, this article introduces the anti-theft system in detail, the encoder / decoder modules. Secondly, the article analyzes the application environment, introduces the meaning of GSM, network structure, working methods and the characteristics of the GSM system, and discusses the TC35 module on the working principle, circuit structure, and working methods. On this basis, the article puts forward the AT commands based on TC35 module, introduces in common AT commands of Multi-function in-vehicle communications and how to achieve the desired results of the paper. Then, the paper describes system structure of Bluetooth agreement and design of hardware and software in core of the 80C51 microcontroller.Hardware circuit design include theftproof module of coding and decoding, peripheral equipment of LCD,keyboard unit, peripheral unit of GSM chip and common AT dictates, Bluetooth jaw circuit. Software design process includes some subprogram modules: display keyboard module, TC35 module and Bluetooth module. Last, the important modules of overall system need to be tested and access to performance testing of GSM network. Test results show that the Bluetooth hands-free communications system work properly and meet the technical requirements of the system design.