Research And Design Of Automobile Virtual Instrument Based On QNX

The driver obtains the relevant parameters in the vehicle's operation in real-time through the automobile instrument and grasps the running status of the vehicle to effectively improve vehicle driving safety.The automobile virtual instrument uses TFT(Thin Film Transistor)liquid crystal display instead of the traditional mechanical and digital composite automobile instrument.The way,through the LCD screen to display the current running information of the vehicle in a variety of ways consistent with the driver's visual habits,not only improves the display of vehicle information accuracy and speed,but also effectively solve the traditional instruments display a single and less information transmission and other shortcomings through a variety of graphics,images and characters.In view of automotive virtual instrumenthardware resource management and software delay control or graphical interface implementation and pointer dynamic display problems,a virtual instrument implementation program based on QNX is aimed to design in the paper,including the following main contents:1.From the core architecture features of the QNX operating system,the principle of the high reliability of the operating system is analyzed in the paper.That is,the driver and the application program are all executed in the user mode,which can effectively avoid the system crash caused by driver or application errors,and ensure operation reliability and security of the entire system.Then,the strong real-time performance of the QNX operating system is tested and analyzed from the three indicators of interrupt response delay,scheduling delay,and context switch delay.2.By studying the specific contents of the universal embedded graphics library implementation technology,a lightweight graphics control library consisting of three-part system which include an event subsystem,an object subsystem,and a graphics subsystem is designed and implemented on the basic graphic interface of GF(Graphics Frame)provided by QNX in the paper,which is an important part of the entire automotive virtual instrument system display.3.A detailed analysis of the functional requirements of automotive virtual instrumentation is carried out in the paper.Based on the comprehensive consideration of the QNX microkernel structural features and hardware platform,a hierarchical software design scheme is adopted.The software design is implemented using a multi-process and multi-threaded software architecture,which can be beneficial to instrument software upgrades and maintenance.The hardware driver layer software is designed based on the POSIX standard to provide a standard file operation function for the client program.Firstly,the middle support layer software is to complete complex data processing and provide a standard call interface for the operating system and upper layer software.Secondly,completing the graphic control library design.It is a bridge that the upper layer graphical interface display software interacts with the hardware of microprocessor graphics controller.According to the specific requirements of the automotive virtual instrument,the application layer software is divided into different task modules.The standardized communication and call methods are used to realize the functions of the virtual instrument.First,the software completes a series of initializations for all hardware modules.Then,the system creates running tasks.The operation system schedules and runs them in real time based on the current state of each task.After completing the design of the above research content,a hardware-in-the-loop test system testing the function and performance of the virtual instrument is set up.The corresponding test cases for virtual instrument submodules are written for testing and analysis.The basic test and analysis of PWM output and CAN communication driver modules are completed.Some of the instrument's functional modules are tested and analyzed based on the test.Finally,the key performance in instrument software design is tested and analyzed.A conclusion is obtained by the analysis of the test results of various parts in the article.All of the functional requirements of the car virtual instrument based on the QNX basic software design are realized in this article.The display and switching of the main dial and the traveling computer interface are normal,which have verified the feasibility of the article's design.