基于单片机的超声波测距——应用于汽车防撞系统近几年来，因为电子科学技术及压电陶瓷材料技术的不断发展，超声检测技术的发展也就十分迅猛。超声波具有定向、聚束以及反射、透射等特性。超声检测技术是利用已知超声波在空气中的传播速度的情况下，测量超声波在发射后直到遇到障碍物反射回来的时间，根据发射和接收的时间差，计算出到障碍物的实际距离。
基于单片机的超声波测距——应用于汽车防撞系统，介绍了包括超声波测距的基本原理、系统框图、超声波发射和接收电路，在提高测距精度的同时，也尽量避免了盲区的产生。通过利用超声波传输过程中距离和时间的关系，并结合51单片机进行控制和数据的采集处理，设计出了能精确测量两点间距离的超声波距离检测系统。系统主要由超声波发射器电路、超声波接收器电路、单片机控制电路、按键电路及显示电路构成。利用所设计出的超声波测距——汽车防撞系统，测试了在行进中的车辆，即当时两车距离过近时，系统会发出声光警报以提示驾驶员进行相应操作。此系统具有检测速度快、简便、容易计算、易于实时控制，并且测量精度高且可实时车距检测等优点。 34102
关键词  超声波  MCU  LED   测距  传感器
毕业论文设计说明书外文摘要
Title Ultrasonic ranging based on MCU application in automobile anti-collision system
Abstract
In the past ten years, due to the development of Electronic Science and technology and piezoelectric ceramic material technology, making ultrasonic testing technology has been very rapid development. Ultrasonic wave has the bunching, orientation and reflection, transmission characteristics. Ultrasonic detection technology is the use of the propagation characteristics of ultrasonic wave in the medium to realize the determination of non acoustic quantity.
Based on MCU ultrasonic ranging applications in vehicle collision avoidance system, introduces the basic principles of ultrasonic ranging and system diagrams, gives ultrasonic transmitter and receiver circuit, through the blind area elimination, in order to improve the precision of the location. Using the relationship between ultrasonic transmission distance and time, using 51 single-chip microcomputer control and data processing, design a precise measurement between two points distance of ultrasonic liquid level detection system. System is mainly composed of ultrasonic transmitter circuit, ultrasonic receiver circuit, MCU control circuit, keyboard circuit and display circuit. The design of ultrasonic ranging automotive anti-collision system, on a moving car from test, collecting at two car distance is too near the system will issue a sound and light alarm prompts the driver to make corresponding response action. This system has the advantages of easy control, reliable operation and high precision,real-time distance detection.
Keywords  Ultrasonic, MCU, LED, location, sensor
目 录
1 绪 论    1
1.1研究的背景    1
1.2研究的主要内容    2
1.3应解决的关键问题    2
2 电路方案论证    3
2.1方案比较    3
2.1.1 激光测距    3
2.1.2 超声波测距    3
2.2电路总体方案    3
3单片机概述    4
3.1 STC89C51主要性能    4
3.2 STC89C51外部结构及特性    4
3.3 STC89C51内部组成    6
4 超声波测距模块    7
4.1 超声波传感器介绍    7
4.2 HC-SR04超声波测距模块的性能特点    8
4.3 HC-SR04的管脚排列和电气参数    9 51单片机的超声波测距系统设计+电路图+代码:http://www.751com.cn/zidonghua/lunwen_31516.html