Design And Implementation Of In-Vehicle Centra Information Management Unit Based On ARM And CAN Bus

In recent years, along with China's rapid economic development, income per capita is growing, people's living standards are improving, purchasing private cars is became as a necessity for the pursuit of a higher quality of life from the car sales in recent years.In the meantime, people demand higher performance of the cars, especially in automotive high-tech products. However, car dashboard which is used in many vehicles does not meet the growing demands of the automotive technology standard, because of its data, poor calability, and many other shortcomings. Central information system, a technique conbined of vehicle and computer, emerges in this background.Generally speaking, in-vehicle central information system refers to high-speed 32-bit CPU processor, displaying data on touch-screen. Because of its low cost, good scalability, varieties data, can solve the disadvantages of the car dashboard.Therefore, using central info-system in vehicle has become an inevitable trend in the future.By understanding the situation of the development of the domestic vehicle information systems, the author designs and realized the in-vehicle information management unit based on ARM and CAN bus. By receiving CAN bus data, the system can analyze the components' traveling data, display it in the QT GUI and save it in real time. Users can export the data log files to Vehicle Administration department for data analysis.So. it is not only for dealing with emergencies and making reasonable judgments, but also facilitating the management of the car. and promoting social modernization.The first chapter is to introduce the historical background of the vehicle information system and current state of development, then introduced one of in-vehicle information system researches, the in-vehicle central information management unit which is based on ARM and CAN bus. Finally, the author addresses the technical problems which are needed to be solved before completing this research project, such as reasonable system design, building cross-compiler environment and so on.Introduced the subject of some of the realistic background, the second chapter introduces the system-related hardware and software development platform, describes cross compiler environment and the SAE J1939 data link layer protocol in detail. Software development platform includes embedded Linux operating system platform. CAN driver. Qt/Embedded technology, and the cross-compiler environment. Hardware development platform includes ARM development board. CAN-bus network. Understanding the development of the system's technical background, this paper made of the overall design of the system according to the system's functional requirements, including the design of daemon program and QT display interface. With respect to the design of deamon program, the author adds a multi-threaded programming to improve the efficiency of the system, creates a FIFO message queue in order to balance the uneven speed of data processing problems between the reader thread and writer thread, imports synchronization mutex semaphore in order to ensure multi-threaded operation no confusion,. With respect to the design of QT display interface, the author works out of the overall design of QT interface and framework map according to mode of function modules.After presents of the overall design of the system in ChapterⅢ, the author completes the specific implementation of the system by coding, including daemon program and QT interface. Part of the daemon program, this paper proposes a global plan at first, and defines and initializes global variables, structure definitions, names the thread according to the overall design. Then through the form of a flowchart, this paper explains the main functions and operation of the thread routine procedure. With respect to QT interface, the author explains the QT interface keypad implementation in detail, in accordance with the function given by the eventual realization of the graphical user interface.Finally, the author Carries out a series of experiments to check the feasibility of the vehicle information system, ensures that the system has good running state and stable feasibility.