基于AT89C51单片机倒车防撞报警系统设

计

摘要

随着社会经济的发展交通运输业日益兴旺，汽车数量在大幅攀升。交通拥挤情况也日趋严重，撞车事件屡屡发生，造成了不可避免的人身伤亡和经济损失，针对这种情况，设计一种响应快，可靠性高且较为经济的汽车防撞预警系统势在必行，超声波测距法是最常见的一种距离测距方法，本文介绍的就是利用超声波测距法设计的一种倒车防撞报警系统。

论文的内容是基于AT89C51单片机结合于一体，设计出一种基于AT89C51单片机的倒车防撞报警系统。该系统采用软、硬件结合的方法，具有模块话和多用化的特点。论文概述了超声波检测的发展及基本原理，阐述了超声波传感器的原理及特性。对于系统的一些主要参数进行了讨论，并且在介绍超声波测距系统功能的基础上，提出了系统的总体构成，通过多种发射接收电路设计方案比较，得出了最佳设计方案，并对系统各个设计单元的原理进行了介绍。对组成各系统电路的芯片进行了介绍，并阐述了它们的工作原理。论文介绍了系统的软件结构，通过编程来实现系统功能。最后，通过对系统的误差分析，给出了系统的改进方案。

关键词：单片机 超声波 AT89C51

Abstract

With the development of society and economy of transportation industry is booming, the number of cars in the sharp rise. Traffic congestion has become more and more serious, the crash occurred repeatedly, resulting from the inevitable casualty and economic loss, in view of this situation, design a kind of fast response, high reliability and more economy car collision avoidance warning system to be imperative, ultrasonic ranging method is the most common type of distance measuring method, this paper describes the use of ultrasonic locating design a back-draft anti-collision alarm system.

The content of the thesis is based on the AT89C51 single-chip integration, design based on AT89C51 back-draft anti-collision alarm system. The system uses a combination of hardware and software, the method of module, and multi-use characteristics. This paper summarizes the development and basic principle of ultrasonic detection, introduces the principle and characteristics of ultrasonic sensor. Some of the main parameters for the system were discussed, and introducing ultrasonic ranging system functions basis, the overall composition of the system, through a variety of transmitting and receiving circuit design comparison, the best design scheme, and various system design unit this paper introduces the principle of. On the composition of the system circuit chip are introduced, and elaborated the principles of their work. This paper introduces the software structure of system, programmed to realize the function of the system. Finally, through the analysis of system error, an improved scheme is presented.

Key words: single chip ultrasonic AT89C51

目录

1超声检测发展综述 ........................................................................................................................ 1 2 超声波介绍 ................................................................................................................................. 2

2.1 超声波传感器及其测距原理 ........................................................................................... 2 2.2 什么是超声波 ................................................................................................................... 2 2.3 压电式超声波传感器简介 ............................................................................................... 2 2.4 频率特性 ........................................................................................................................... 4 2.5 指向特性 ........................................................................................................................... 5 3 单片机倒车防撞报警系统各组成单元方案设计 ..................................................................... 6

3.1 发射接收电路方案设计 ................................................................................................... 6 3.2 系统显示电路设计 ........................................................................................................... 7 3.3 系统报警电路设计 ........................................................................................................... 7 3.4 单片机复位电路 ............................................................................................................... 8 3.5 时钟电路 ........................................................................................................................... 9 3.6 稳压电源 ........................................................................................................................... 9 4 系统硬件及软件实现 ................................................................................................................. 10

4.1 单片机的选择 ................................................................................................................. 10 4.2 AT89C51的主要性能参数 .............................................................................................. 10 4.3 AT89C51的结构 .............................................................................................................. 10 4.4 CX20106芯片介绍 .......................................................................................................... 11 4.5 系统软件结构 ................................................................................................................. 12 4.6 硬件连接方法 ................................................................................................................. 12 4.7超声波发射程序 .............................................................................................................. 12 4.8 超声波接收及显示程序 ................................................................................................. 13 4.9 1602显示初始化写指令写数据程序 ............................................................................ 14 4.10 蜂鸣报警程序 ............................................................................................................... 18 结束语 ............................................................................................................................................ 19 谢词 ................................................................................................................................................ 20 参考文献......................................................................................................................................... 21