CAN Bus Based Body Control System Automotive Research and Application

Abstract: CAN, all known as the "Controller Area Network", the Controller Area Network, is the most widely used international fieldbus one. CAN was originally appeared in the automobile industry in the late 80s, first put forward by the German Bosch company. CAN is a multi-master mode serial communication bus, the basic design requires a high bit rate, high resistance to electromagnetic interference, and can detect any error. When the signal when the transmission distance of up to 10km, CAN can provide up to 50Kbit / s data transfer rate. CAN bus has become the current international standard, widely used in European and American cars, is recognized as some of the most promising one field bus.

I. Introduction

Scientific development makes car is increasing the threat Yuelaiyueduo the function of Ru He makes a number of independent features such harmonization, that is how the body of the Zheng Ge Jinxingkongzhi, Yijingchengwei the entire field of automotive electronics research a very important issue. Automotive network that car bus technology has emerged in this environment. The CAN bus technology for its high real-time, high reliability in a variety of vehicle control bus came out top.

Second, CAN Bus Description

CAN, all known as the "Controller Area Network", the Controller Area Network, is the most widely used international fieldbus one. CAN was originally appeared in the automobile industry in the late 80s, first put forward by the German Bosch company. Yes a multi-Zhu Fang Shi CAN serial communications bus, the basic design specifications with Gao's bit rate, high resistance to electromagnetic Ganrao Xing, and Nenggoujiance the production of Renhecuowu. When the signal when the transmission distance of up to 10km, CAN can provide up to 50Kbit / s data transfer rate. CAN bus has become the current international standard, widely used in European and American cars, is recognized as some of the most promising one field bus.

Third, the system design

Targets automotive body control of the system include: 4 car door locks, two or more window lift, luggage lock, defrost heater, electric mirrors, front and rear lamps, small lamps, turn signals, hazard lights, fog lights, license lights, interior reading lights, dome light, etc. inside. In the case of functions with remote control, also includes remote control signal reception processing and the control anti-theft system. Therefore, according to the above each function to be completed, this system is designed for five sub-modules, namely, central control module (realized in the control door locks, security, wipers, lights and the rear window and outside mirror heating and other functions), 4 door control module (main drive door modules, respectively, right front door modules, door modules left and right rear door modules, to control the window lifter and door locks). Figure 1 shows the body control module CAN bus architecture.

CAN Bus Based Body Control System Automotive Research and Application

4, Body Control System Based on CAN bus hardware development

(A) circuit diagram of each module

Based on the above design is divided into five sub-modules.

Master control unit receives the signal after switching, the first analysis and processing, and then send the CAN bus to control commands to the controlled side, after the controlled-side response to the corresponding movement.

The following is a circuit diagram of each module shown in Figure 2, Figure 3, Figure 4.

CAN Bus Based Body Control System Automotive Research and Application

CAN Bus Based Body Control System Automotive Research and Application

CAN Bus Based Body Control System Automotive Research and Application

(B) main components used in

(1) CAN controllers. Taking into account the need to expand the system, we use PHILIPS SJA1000 produced as the system CAN controller. It CAN controller and PCA82C200 independent pin-compatible, but also and PCA82C200 independent CAN controller electrical compatible; both support the Basic CAN mode and also supports PeliCAN model; and CAN2.0B agreements compatible; can support 11-bit and 29-bit identifier ; bit rate up to 1Mbits / s.

(2) CAN transceiver. With PHILIPS company TJA1050, as with PCA82C250, TJA1050 meet ISO11898 standards, but it is critical of radiation on the AM band lower than PCA82C250 more than 20dB. When the power is not rendered passive characteristics of the bus.

(3) SCM. By P89C51. The microcontroller is derived 80C51 microcontroller device is manufactured using advanced CMOS process 8-bit microcontroller, 80C51 instruction set and the same.

5, based on CAN Bus Body Control system software development

In the CAN BUS system, the user is required to write according to their own application layer and user layer software. User-level control strategy to achieve the user requirements and systems, and application layer is between the user level and interfaces, CAN set up a message transmission method of the time, signal levels and protocol, application layer defines the structure, response and reporting the meaning of the text, the application layer CAN system according to the different applications vary.
(A) CAN controller initialization

CAN controller SJA1000 send and receive signals in the official must be initialized before the set. Initialization of the SJA1000 is work, receive filter register, receive mask register, register to receive the code, the baud rate setting parameters, requires written content of each register careful and comprehensive consideration. The initialization process shown in Figure 5.

CAN Bus Based Body Control System Automotive Research and Application

(2) CAN bus to send and receive data

After the success of the SJA1000 initialization, you can use it to transmit and receive messages. Node sends messages to the bus is the process: SCM P89C51 will send the data to be formatted according to the composition of a CAN message, write SJA1000 sending buffer, and then start the SJA1000, the message sent to the bus up. The process of receiving messages is: SJA1000 from the bus automatically receive messages, and have been filtered into receive buffer, an interrupt request to the MCU, MCU reads the packet from the buffer. Sending and receiving process shown in Figure 6, Figure 7.

CAN Bus Based Body Control System Automotive Research and Application

CAN Bus Based Body Control System Automotive Research and Application

VI Conclusion

CAN bus with its high performance, high reliability and unique design more and more attention has been paid, and was recognized as a vehicle electronic control system in one of the most promising of the bus. As a reliable Automotive Computers 網絡 bus has advanced in Xuduo car 得到, enabling Ge Automotive Computers Kongzhidanyuan CAN bus can be shared by Suo You 信息, and resources to achieve Jianhua wiring, reducing the number of sensors to avoid the control Gongneng 重復, increase system reliability and maintainability, lower costs, better matching and coordination of the various control purposes.