摘要超声波是指频率高于20000赫兹的声波。超声波属于机械波范畴，因而也遵循一般机械波在弹性介质中的传播规律，如在折射率不同的介质分界面处发生反射和折射，在进入介质后被介质吸收而发生衰减等，此外，超声波具有方向性好声能集中等特点。基于以上性质和特点，超声波具有用于距离的测量的理论基础。63683

课题任务中，系统的设计主要是通过软件程序来实现超声波发射接收测距的功能。设计目标是采用PIC16F877a单片机编写超声波发射接收测距和温度测控的程序以实现测距功能。整个程序一般编程采用的自顶向下的设计思想，主函数控制所有功能，各功能的实现分别使用对应的函数来完成，包括超声波的发射和接收、I/O口初始化、LCD显示、温度检测。程序控制单片机进行数据发送与接收，并将实现数据正确显示在LCD上。

毕业论文关键词  超声波测距  软件程序  PIC16F877a

毕业设计说明书（论文）外文摘要

Title   The Software Designing of Ultrasonic Ranging System                    

Abstract Ultrasonic Wave is a kind of wave that the frequency is more than 20000Hz. Ultrasonic Wave belongs to the area of mechanical wave, and thus follows the general mechanical wave propagation in elastic medium, such as occurring reflection and refraction at the interface of different mediums with their own refractive indexes and attenuation by absorption of the index after entering it. Furthermore, Ultrasonic Wave has good directionality and high concentration of sound energy. Based on the properties and characteristics above, Ultrasonic Wave has the theoretical foundation of being used in the measurement of distance. 

    In the mission of the issue, the system design is mainly based on the software program which controls the function of Ultrasonic Wave launching and receiving. The design target is compiling the launching, receiving and measuring software program by using single chip PIC16F877a to achieve the ultrasonic ranging correctly. The whole project employs the idea of top-down designing. The main function controls all the program, and each function achieves by corresponding software function, including ultrasonic launching and receiving, initialization of the I/O, LCD display and temperature detection. The single chip transmitting data is controlled by the program and data are displayed correctly on the LCD screen.

Keywords  Ultrasonic Ranging technology  software program  PIC16F877a

1  绪论… 1

1.1  课题的研究背景… 1

1.2  课题的概述… 1

1.3  课题的应用前景… 2

1.4  本章小结 2

2  课题所涉及的部分理论原理… 3

2.1  人耳分辨的声波频率范围… 3

2.2  超声波的应用特点 3

2.3  超声波测距的原理 3

2.4  本章小结 5

3  软件程序编程语言选择… 6

4  课题所使用的相关软件… 8

4.1  单片机PIC16F877a 8

4.2  编程软件MPLAB IDE… 9

4.3  单片机编译器PICC… 10

4.4  USB下载驱动 11

4.5  本章小结… 12

5  软件功能 13

5.1  概述… 13

5.2  超声波的发射和接收 14

5.3  测距时间到距离的换算程序… 16

5.4  液晶显示程序… 17

5.5  本章小结… 18

6  程序的编译处理… 19

6.1  程序编译… 19

6.2  下载烧写… 20

6.3  测距数据… 22