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基于单片机的超声波测距仪的设计与实现

中文摘要

本设计基于单片机AT89C52，利用超声波传感器HC-SR04、LCD显示屏及蜂鸣器等元件共同实现了带温度补偿功能可报警的超声波测距仪。我们以AT89C52作为主控芯片，通过计算超声波往返时间从而测量与前方障碍物的距离，并在LCD显示。单片机控制超声波的发射。然后单片机进行处理运算，把测量距离与设定的报警距离值进行比较判断，当测量距离小于设定值时，AT89C52发出指令控制蜂鸣器报警，并且AT89C52控制各部件刷新各测量值。在不同温度下，超声波的传播速度是有差别的，所以我们通过DS18B20测温单元进行温度补偿，减小因温度变化引起的测量误差，提高测量精度。超声波测距仪可以实现4m以内的精确测距，经验证误差小于3mm。 关键词：超声波；测距仪；AT89C52；DS18B20；报警

Design and Realization of ultrasonic range finder based

ABSTRACT

The design objective is to design and implement microcontroller based ultrasonic range finder. The main use of AT89C52, HC-SR04 ultrasonic sensor alarm system complete ranging production. We AT89C52 as the main chip, by calculating the

round-trip time ultrasound to measure the distance to obstacles in front of, and displayed in the LCD. SCM ultrasonic transmitter. Then the microcontroller for processing

operation to measure the distance and set alarm values are compared to judge distance, when measured distance is less than the set value, AT89C52 issue commands to control the buzzer alarm, and control each member refresh AT89C52 measured values. Because at different temperatures, ultrasonic wave propagation velocity is a difference, so we DS18B20 temperature measurement by the temperature compensation unit, reducing errors due to temperature changes, and improve measurement accuracy. Good design can achieve precise range ultrasonic distance within 4m, proven error is less than 3mm. Keywords:Ultrasonic；Location；AT89C52;DS18B20;Alarm

目录

第一章 前言 .................................................................................................................................................... 1

1.1 课题背景及意义 .............................................................................................................................. 1

1.1.1超声波特性 .............................................................................................................................. 1 1.1.2超声波测距 .............................................................................................................................. 2 1.2 超声波模块基本介绍 ........................................................................................................................ 3

1.2.1 超声波的电器特性 ............................................................................................................... 3 1.2.2 超声波的工作原理 ............................................................................................................... 4 1．3主要研究内容和关键问题 .............................................................................................................. 5 第二章 方案总体设计 .................................................................................................................................... 7

2.1 超声波测距仪功能 ............................................................................................................................ 7 2.2设计要求............................................................................................................................................. 8 2.3系统基本方案 ..................................................................................................................................... 9

2.3.1方案比较 .................................................................................................................................. 9 2.3.2方案汇总 ................................................................................................................................. 11

第三章 系统硬件设计 .................................................................................................................................. 13

3.1 单片机最小系统 .............................................................................................................................. 13 3.2 超声波测距模块............................................................................................................................. 13 3.3 显示模块 .................................................................. 14 3.4温度补偿电路 ............................................................... 15 3.5 蜂鸣报警电路................................................................................................................................. 16 第四章 系统软件设计 .................................................................................................................................. 17

4.1 AT89C52程序流程图 ...................................................................................................................... 17 4.2 计算距离程序流程图 ...................................................................................................................... 19 4.3 报警电路程序流程图 ...................................................................................................................... 19 4.4 超声波回波接收程序流程图 .......................................................................................................... 19 第五章 系统的调试与测试......................................................................................................................... 20

5.1 安装.................................................................................................................................................. 20 5.2 系统的调试...................................................................................................................................... 20 第六章 总结 .................................................................................................................................................. 22 参考文献 ........................................................................................................................................................ 23 致 谢 ........................................................................................................................... 错误！未定义书签。 附录 ................................................................................................................................................................ 25

附录1 整机电路原理图 ........................................................................................................................ 25 附录2 超声波温度和速度的关系 ........................................................................................................ 26 附录3 部分源程序................................................................................................................................ 28