Embedded Performance Detecting System For Automotive Switch

This paper is developed by the horizontal issue "auto switching performance detection system". Aiming at the delay bottleneck caused by the phenomenon that the speed transmissing between microprocessor and PC is slower than microcontroller processing speed in the traditional detecting system of auto switching performance, the paper carries out thorough research on the multichannel data acquisition technology, Internet technology used in the embedded field and virtual instrument technology to design the embedded detecting system of auto switching performance based on ARM9and Lab VIEW. The system actualizes the Ethernet communication between the data acquisition module of lower computer and the host PC and raise the transmissing speed from traditional140Kb/s to IMb/s or more.Meanwhile, it adopts the virtual instrument technology to achieve PC monitoring system that can display detection result in real-time. The main work of this paper includes the data acquisition design of lower machine, drive design of network communication and monitoring system design of host PC.I The data collecting module of lower computer from the system includes:①The ARM9control collecting module:the RISC processor S3C2440A from Samsung in16/32bit is selected as the main controller, using its built-in AD convert in high precision and controlling the input and output signals in analog or digital with its multichannel and multifunctional I/O; it select DG408,74HC573,74F245and other digital circuit chip to control the transmission direction and timing in simple structure and stability.②The ethernet interface module:the ethernet control chip DM9000AEP connects with S3C2440A in indirect bus and connects with HR91005through coupling transformation circuit to transmit network packets, achieving ethernet communication with the host PC.③The peripheral circuit module:the current signal of switch conduction is converted to the voltage signal through the holzer current sensor and transferred to AD input pin from S3C2440A after the sample-hold and optical coupling circuit; the digital signal outputed from S3C2440A uses darlington transistor to drive the electric relay for switching the load to correct the voltage drop.Ⅱ The drive design of network communication from the detecting systemThe embedded real-time operating system μC/OS-Ⅱ is chosen as the software platform between the underlying hardware of S3C2440microprocessor and the upper application, the lightweight network protocol LWIP is transplanted to μC/OS-Ⅱ system and the DM9000AEP drive and socket communication program in application layer are added to actualize the network communication function, ultimately raising transmitting speed to trillion level.III The design of PC monitoring part from the detecting systemThe American NI graphical software development environment Lab VIEW is used to design PC monitoring system for the performance detection system of vehicle switch combining with the Internet technology. It has the advantage of hort development cycle and supporting network protocols such as TCP, UDP to achieve remote data sharing of test results.