摘要随着科学的发展我们有很多地方不再用传统测距方法了。由于很多地方传统的测距方法根本无法完成正确的测量任务，比如：深井，液体，管道长度等场合，于是我们发现了一个新的测距方法超声波—非接触测距。  超声波可以非接触测距也不会受电，磁，光等因素的干扰。42147

由于超声波不容易被干扰，方向是比较好的，能量消耗也比较小，工作距离较远，基本取代了传统测距仪器。  

现在人们的经济水平不断提升，很多人都有了自己的汽车。由于拥有汽车的人变多道路显得很拥挤，难免发生跟别人车擦碰尤其是在倒车过程中。因此发生汽车损坏，人员伤亡等麻烦。如果这里有测跟其它车和障碍物距离的硬件我们就减少遇到这种麻烦。因此我们意识到了超声波在这发面的作用了，设计了超声波汽车防撞装置系统。

本课题是用的是89C52单片机的超声波测距仪，成本相对比较低廉，而且性能较好，可以有效的解决倒车时遇到的问题。 

毕业论文关键词： 测距   单片机  超声波

Ultrasonic Range Finder

Abstract

Now science is developing faster and faster, I have many places no longer use the traditional methods, such as: ranging

Due to the many local traditional ranging method is simply unable to complete the correct measurement tasks, such as: deep, liquid, length of pipe occasions. So we have found that the a new ranging method ultrasonic non contact measuring. Ultrasonic waves can be non-contact ranging and will not be affected by electrical, magnetic, optical and other factors.

Because the ultrasonic is not easy to be disturbed, the direction is relatively good, the energy consumption is relatively small, the working distance is far, basically replaced the traditional distance measuring instrument.

Now people's economic level rising, many people have their own cars. Because people who have cars become more crowded, it is inevitable to happen with someone to rub the car, especially in the process of reversing. So the car damage, casualties and other troubles. If there is a test with other cars and obstacles away from the hardware . The designed ultrasonic anticollision device for vehicle system.

This topic is using the 89C52 microcontroller ultrasonic distance measuring instrument, the cost is relatively low, and the performance is good, can effectively solve the problems encountered when reversing.

Key Words:  Ultrasonic  Microcontroller

目  录

摘  要 I

Abstract II

目  录 III

1.绪论 1

1.1  课题背景及意义 1

1.2  国内外研究现状 1

1.3  课题研究内容及章节安排 2

2  总体方案论证 3

2.1 设计方案论证 3

2.2  系统方案 4

2.3  AT89C52芯片、超声波简介 4

3  硬件设计 6

3.1 硬件电路 6

3.2复位电路 6

3.3显示电路 7

3.4超声波发射与接收电路 7

4软件设计 9

4.1计算距离程序 9