The Design And Application Of Vehicle Terminal Based On Embedded System Platform

With the increasing holdings of automobile, reasonable traffic scheduling and intelligent navigation service become the essential conditions for the drivers. Vehicle navigation is a hot issue in automotive electronics industry. Embedded processor as a terminal equipment can realize multifunctional scheduling and realtime information processing, the embedded processor can provide timely navigation service for the user. This article construts an embedded operating system platform which is based on the ARM7processor and μC/OS-Ⅱ real-time operating system kernel, designs and implements a vehicle terminal system.Vehicle terminal has the characteristics of complex application function and frequent information scheduling. In the design, ARM7processor has a high data processing ability, μC/OS-II priority-based preemptive kernel can implement multitasking scheduling, which can meet the requirments of vehicle terminal. When the high-priority task is applying for the critical resources which are occupied by the low-priority task, μC/OS-Ⅱ kernel scheduling accompanies with priority inversion problem. A new method based on dynamic switching of multitask is presented in this paper. The task state is changed dynamically to achieve the switching of the middle-priority ready task between the ready list and the waiting list. The priority ceiling method will affect the normal scheduling of the kernel by changing the priority of the task. The round-robin method is complex andinefficiency. Dynamic switching idea is introduced to avoid these deficiencies, which can enhance the efficiency of multitask scheduling. This paper transplants the improved kernel onto the processor based on ARM7and constructs the real-time operating system platform with graphical interface system, file system and network system. According to the importance of function and the protection of share information, the system manages different tasks which include graphical interface, file, GPS and network communication, and finally designs embedded vehicle terminal to realize the electronic map navigation application.The test results show that modified kernel can solve the priority inversion problem in the vehicle terminal, and the system will operate stably. The execution efficiency of vehicle terminal system is improved obviously.