摘要
超声波是频率高于 20KHZ 的声波具有指向性强，能量消耗缓慢，在介质中传播的距
离较远，因而超声波经常用于距离的测量，如测距仪和物位测量仪等都可以通过超声波来
实现.利用超声波检测往往比较迅速、方便、计算简单、易于做到实时控制，并且在测量
精度方面能达到工业实用的要求，因此在液位、井深、管道长度的测量、移动机器人定位
和避障等领域得到了广泛的应用。基于此，本次设计尝试使用 AT89S52 与 HC-SR04 模块
来实现超声波的测量,结合外围电路模块实现距离显示及报警构成超声波测距系统。
本次超声波测距系统由单片机计时及控制电路、超声波发射接收模块、测量距离显示
电路、报警电路等部分组成。详细介绍了超声波测距模块及 AT89S52 单片机的测距原理。
以 HC—SR04 超声波测距模块为核心实现超声波的发射与接收.显示电路采用数码管以及
三极管显示控制，报警电路由蜂鸣器与三极管组成.整体电路结构简单，成本低廉，工作
稳定,测量精度也达到实际应用要求。
关键词：超声波 测距 单片机 HC-SR04
Abstract
Ultrasound is sound waves with frequency higher than 20KHz, it has strong directivity and
consumes energy slowly, at the same time it spreads farther in the same medium. Therefore
ultrasound is often used for distance measurement ， such as the range finder and level
measurement and so on can be achieved by it。 Use of ultrasonic detection tends to be quickly,
convenient and simple calculation ， easy to do real—time control 。 In the measurement
precision it can reach industry practical requirement。 So in liquid level, well depth， pipe
length measurement， mobile robot localization and obstacle avoidance, etc a wide range of
applications.
This ultrasonic ranging system consists of the single—chip microcomputer timer and
control circuit， ultrasound transmitting and receiving modules, the distance display circuit，
alarm circuits and other components. Detailed introduces the ultrasonic ranging module and
AT89S52 MCU range finder principle. HC-SR04 is the core of the ultrasonic transmitter and
receiver。 The result displays with digital tube and controlled by transistor。 And the alarm
circuit is composed by buzzer and transistor. The whole circuit is simple structure, low cost，
stable work and the measurement accuracy reached the application requirements.
Key words: ultrasonic wave ranging MCU HC—SR04
