摘要随着经济以及科学技术的发展，现代车辆的使用数量急剧增加，车辆的电控 系统、用电设备也越来越复杂，由此带来了成本的提高、可靠性降低等问题。所 以车载网络成为了现代汽车发展的必然趋势。为了简化车辆上的电气设备的线 缆，提高车辆电控系统的可靠性与灵活性，总线技术应运而生。其中 CAN 总线 技术成为了车载网络系统最流行的的现场总线之一。本课题基于 CAN 总线设计了 车载网络故障诊断仪。72691

本课题阐述了车载网络诊断系统的研究背景、国内外发展以及 CAN 总线技术 的发展。另外，本课题还完成了车载网络诊断系统的硬件设计。其根据需要，采 用 AT89C51 单片机作为核心部分，82C250 实现 CAN 报文的收发，并用 LCD 液晶 用于信号的显示。而软件设计，采用了模块化的编程思想，每一个功能模块实现 一个独立的功能。最后，对车载网络诊断系统进行调试分析。

毕业论文关键词：车载网络；CAN 总线；故障诊断

Design of Vehicle Network Fault Diagnosis Instrument Based on CAN Bus

Abstract With the development of economy and science and technology, the use  of modern vehicles has increased dramatically, the electric control system of the vehicle, the electric equipment is more and more complex。,which brings the cost of the increase, reliability and other issues。 So the car network has become the inevitable trend of the development of modern cars。In order to simplify the electrical equipment on the vehicle cable, improve the reliability and flexibility of the vehicle electronic control system, bus technology came into being。 Among them, CAN bus technology has become one of the most popular field bus in the vehicle network system。Based on the CAN bus, this paper designs the vehicle network fault diagnosis instrument。

This topic describes the research background, domestic and foreign development and the development of CAN bus technology。In addition, the paper also completed the hardware design of the vehicle network diagnosis system。 According to the need, the use of AT89C51 microcontroller as the core part,82C250 to achieve CAN message transceiver, and using LCD liquid crystal for signal display。And the software design, using the modular programming ideas,each function module implements an independent function。Finally, the vehicle network diagnosis system is debugged and analyzed。

Key Words: Vehicle network; CAN bus; fault diagnosis

目 录

摘 要 I

Abstract II

目 录 III

1 绪论 1

1。1 研究目的与意义 1

1。2 研究现状 2

1。3 课题的主要内容及实施方案 4

1。4 本章小结 5

2 CAN 总线协议 6

2。1 CAN 总线定义 6

2。2 CAN 总线的报文定义 8

2。3 CAN 总线的通信协议 10

2。4 本章小结 10

3 诊断系统硬件设计 12

3。1 设计方案 12

3。2 单片机最小系统 12

3。3 电源电路设计 16

3。4 按键模块设计