摘  要：随着社会经济的发展和交通运输业的不断兴旺，汽车的数量在不断的增加。交通拥挤状况也日益严重，撞车事件也经常发生，造成了很多不可避免的人声伤亡和经济损失，面对这种情况，设计一种响应快、可靠性高并且比较经济的汽车防撞预警系统显得非常的重要。超声波测距法是一种最常见的距离测量方法。本文介绍的就是利用超声波测距法设计一种倒车防撞报警系统。

　本文的内容是基于超声波测距的倒车防撞系统的设计，主要是利用超声波的特点和优势，将超声波测距系统和STC89C52单片机结合于一体，设计出一种基于STC89C52单片机得倒车防撞系统。运用DS18B20温度补偿系统来精确测距，最后在LCD液晶上显示距离。系统采用软硬结合的方法，具有模块化和多用化的特点。

　本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。

关键词：倒车防撞；超声波；测距；STC89C52

Abstract

　With the social and economic development and transportation continues to boom, the automobile quantity climbs in the first mate. Traffic congestion condition also day by day serous, the collision event occurred repeatedly, has caused the inevitable person casualties and the economic loss, in view of this kind of situation, designed one kind to respond quickly, the reliability was high also a more economical automobile guards against hits the early warning system imperative, the ultrasonic wave range finding was the most common one distance range finder method, this article introduces is guards against using the ultrasonic wave range finding design one kind of reversing collision avoidance system.

　The paper is based on the ultrasonic distance reversing collision avoidance system design, mainly using ultrasound features and advantages, ultrasound ranging system and the integration with the integration STC89C52 monolithic integrated circuit, STC89C52 monolithic integrated circuit based on the design of a reverse collision avoidance warning systems. Using the DS18B20 temperature compensation system to the precise range, and finally displayed on the LCD distance.The system used software and hardware integrated approach of modular and multi-use characteristics.

　The paper outlines the development and the basic principles of ultrasound tests on the principles and characteristics of ultrasound sensors. Some of the main parameters for the system were discussed, and introducing ultrasonic ranging system functions basic, the overall composition of the system. Through multiple launch reception circuit design comparison, the best designed programme drawn, and various system design modules principles introduced. On the composition of the system circuit chip introduced and elaborated the principles of their work. Papers introduced system software architecture, through programming to achieve system function.

　Key word: reversing collision avoidance; ultrasonic wave； range finder；STC89C52