摘 要：本设计是以单片机技术为基础，实现对前方物体距离的测量。根据超声波指向性强，能量消耗慢，在介质中传播距离远的特点，利用超生波传感器对前方物体进行感应，经过单片机中的程序对超声波传感器发射和接收的超声波信号进行分析和计算处理，最后将处理结果在LCD1602上显示。STC89C52单片机的超声波汽车倒车防撞报警系统，此系统根据超声波在空气中传播反射原理，把超声波传感器作为接口部件，利用超声波在空气中传播的时间差来测量距离，设计了一套超声波检测系统。该系统设计主要由主控制器模块、超声波集成模块和显示模块等三个基本模块构成。本设计利用两个中断，在发射信号时，打开定时器中断0和外部中断0使定时器计时，接收到发射超声波信号时，外部中断0关闭中断，这时定时器中断0计录的时间就为超声波传播经过汽车倒车防撞报警系统到前方物体的来回时间。利用公式S=T×V／2（V为超生波传播速度，本设计设定值340m/s），经过单片机处理得到距离值S并且通过LCD1602显示出来。66711

毕业论文关键词：单片机STC89C52，HC-SR04超声波传感器，LCD1602

Abstract：The design is based on microprocessor technology to achieve the right measurement of the front object distance. Due to strong directional ultrasonic， energy consumption slow， transmission distance is far in medium use of ultrasound sensors on the front induction objects， SCM logic analysis and calculation through the procedures of ultrasonic sensors transmitting and receiving ultrasonic signals. Finally， after processing the data is in the digital LCD tube. Ultrasonic Ranging System Based on STC89C52 .The ultrasonic system based on the air-borne reflection principle ，ultrasonic sensors are interface components， used the time gap ultrasonic wave transmit in the air to measure distance with application of SCM technology， be able to design a set of ultrasonic detection system. A controller module design， ultrasonic transmitter module design， ultrasonic receiver and display module 4 module is the system design work. Papers presented the design through ultrasonic sensor (non-contact measurement) measurement ultrasonic sensors are fat Radio emission of ultrasonic， with some receiving ultrasonic receiver and alarming device. To overcome the main problem is how to make the measure distance between 0.27 and 4 meters. Use formula S=T × V (V is the ultrasonic wave’s velocity. The design settings 340m/s) microprocessor dispose the distance value displayed on the LCD.

Key words：MicrocontrollerSTC89C52，Ultrasonic transducerHC-SR04，LCD1602

目   录

1 绪论 4

1.1 研究的目的及意义 4

1.2 超声波检测技术发展综述 4

1.3 本课题研究的内容 5

2 超声波测距总体设计方案 5

2.1 方案选择 5

2.2 超声波测距仪的设计思路 5

3 系统主要硬件设计 6

3.1 HR-SR04超声波集成模块 6

3.3 时钟电路 9

3.4 按键电路 10

3.5 蜂鸣器电路 10

3.6 LCD显示电路 11

3.7 系统整体电路 13

4 系统软件设计 13

4.1 系统程序的结构