Software Design Of Vehicle Bluetooth Hand-free System

With the development of the automotive technology, the safety and convenience of vehicles are becoming more and more concerned. The continuous advancement of bluetooth technology makes both of them come true, since which the Bluetooth hands-free system has been widely used in the automotive sector.The contradiction between driving and phoning prompts people to seek various means of achieving vehicle hands-free functionality, however, the stability and real-time are the key issues of vehicle hands-free system, both of which have become a meaningful research question in the automotive electronics field. In order to solve the problem of stability and real-time of the bluetooth hands-free car kit, embedded Vehicle Bluetooth Hands-free System software design was adopted in this paper,μC/OS-II real-time operating system was embedded in the system, and the whole process was divided into many tasks, the system would give different priority degrees to different tasks according to their importance, allowing the system to always run the highest priority task, because of this operation and scheduling mechanisms of embedded operating systemμC/OS-II, the system's real-time was enhanced. Procedures of the system will be divided into seven tasks, namely, initialization task, button scan task, button handle task, bluetooth send task, bluetooth receive task, voice send task and voice receive task, key codes will be sent from button scan task to button handle task to be dealt with through message queue, and then corresponding bluetooth commands will be sent from button handle task to bluetooth send task to be carried out, when bluetooth receive task receives the return instructions of bluetooth module in the way of serial port's interruption, corresponding speech synthesis text will be send to voice send task, finally, voice receive task will receive the responses of speech synthesis chip through serial port's interruption to determine the correctness of synthesis. And bluetooth receive task will be set to receive the highest priority according to the importance degree of the implementation, thus ensuring the implementation of the bluetooth receiver systems forever until other higher-priority task will be performed when this task is suspended. Experiments have shown that system will not only achieve a vehicle bluetooth hands-free function, according to the scheme of system state transition diagram and programming of upper application software procedures, but also will have a better reliability, stability and real-time.