摘  要：现代生活中，汽车逐渐的走入了千家万户，这也就带来了频发的汽车事故，汽车事故的发生不仅会对人们的生命与财产造成严重的伤害，跟给受害者与肇事者的家庭带了不可逆的破坏。倒车测距仪作为时代发展的产物，能够大大的降低由于倒车而引发的交通事故。

倒车测距仪是一种以单片机为控制中心的汽车倒车安全保障装置。该装置将单片机的实时监控与数据处理功能，与超声波传感器相结合，运用超声波测距技术，从而实现测量并计算示汽车尾部与障碍物之间的距离并予以显示的功能。

本文是一款运用超声波作为测距工具的倒车测距仪。设计中采用AT89C52单片机作为控制核心，并选用T/R-40-16超声波传感器作为主要输入，以型号JM12864J的LCD显示器作为主要输出。并辅以数据放大电路及报警电路，达成了能够有效的测量并加以显示的功能型仪器。

本文共有图16个，表5个，参考文献30篇。

关键词：单片机  AT89C52  测距仪

Digital ultrasonic reversing distance finder

Abstract：In modern life, cars gradually enter thousands of households, which also brings frequent car accidents, car accidents will not only cause serious damage to people's lives and property. It brings irreversible damage to the families of the victims and the perpetrators. As a result of the development of the times, the reversing distance finder can greatly reduce the traffic accidents caused by reversing.

The reversing distance finder is a kind of automobile reversing security device with single chip microcomputer as the control center. The device combines the real-time monitoring and data processing function of single chip computer with ultrasonic sensor, and uses ultrasonic ranging technology to realize the function of measuring, calculating and displaying the distance between the rear end of the car and the obstacle.

This paper is a back - up range finder using ultrasonic wave as the distance measuring tool . AT89C52 single - chip microcomputer is used as the control core in the design , and the T / R - 40 - 16 ultrasonic sensor is used as the main input , and the LCD display with the model number of J12864J is used as the main output . The data amplifying circuit and the alarm circuit are supplemented , and the functional instrument can be effectively measured and displayed .

There are 16 figures, 5 tables and 30 references in this paper.

Keywords: single chip microcomputer   AT89C52  distance finder 

目   录

摘  要 I

Abstract II

1 绪论

1.1 课题研究背景及意义 1

1.2 国内外研究现状 1

1.3研究内容及论文的安排 2

2 总体设计方案 3

2.1 超声波测距介绍 3

2.2 系统总体设计思想及设计方框图 3

2.3系统方案选定 4

3 系统硬件设计 6

3.1本章概论 6

3.2 单片机介绍 6

3.3 超声波发射及接收电路设计 8

3.4 放大电路设计 9

3.5 超声波接收电路 11

3.6 LCD显示电路设计 11

3.7报警电路设计