摘  要

    隨著社會經(jīng)濟的發(fā)展交通運輸業(yè)日益興旺，汽車的數(shù)量大幅攀升。交通擁擠狀況也日益嚴重，撞車事件屢屢發(fā)生，造成了不可避免的人生傷亡和經(jīng)濟損失，針對這種情況，設計一種響應快，可靠性高且較為經(jīng)濟的汽車防撞預警系統(tǒng)勢在必行，超聲波測距法是最常見的一種距離測距方法，本文介紹的就是利用超聲波測距法設計的一種倒車防撞報警系統(tǒng)。控制系統(tǒng)核心部分就是超聲波測距儀的研制。因此，設計好的超聲波測距儀就顯得非常重要了。

　　　本設計采用以AT89C51單片機為核心的低成本、高精度、微型化數(shù)字顯示超聲波測距儀的硬件電路和軟件設計方法。整個電路采用模塊化設計，由主程序、預置子程序、發(fā)射子程序、接收子程序、顯示子程序等模塊組成。各探頭的信號經(jīng)單片機綜合分析處理，實現(xiàn)超聲波測距儀的各種功能。在此基礎上設計了系統(tǒng)的總體方案，最后通過硬件和軟件實現(xiàn)了各個功能模塊。相關部分附有硬件電路圖、程序流程圖。

　　　設計通過多種發(fā)射接收電路設計方案比較，得出了最佳設計方案，并對系統(tǒng)各個單元的原理進行了介紹。對組成系統(tǒng)電路的芯片進行了介紹，并闡述了它們的工作原理。論文介紹了系統(tǒng)系統(tǒng)的軟件結構，通過編程來實現(xiàn)系統(tǒng)功能。最后，通過對系統(tǒng)的誤差分析，給出了較完善的方案。

　　

　　關鍵詞：AT89C51; 超聲波；測距                           Abstract


　　With the development of science and technology, the improvement of people's standard of living, speeding up the development and construction of the city. urban drainage system have greatly developed their situation is constantly improving. However, due to historical reasons many unpredictable factors in the synthesis of her time, the city drainage system. In particular drainage system often lags behind urban construction. Therefore, there are often good building excavation has been building facilities to upgrade the drainage system phenomenon. It brought to the city sewage, and it is clear to the city sewage and drainage culvert in the sewage treatment system. comfort is very important to people's lives. Mobile robots designed to clear the drainage culvert and the automatic control system Free sewage culvert clear guarantee robot, the robot is designed to clear the culvert sewage to the core. Control System is the core component of the development of ultrasonic range finder. Therefore, it is very important to design a good ultrasonic range finder.  

　　At the core of the design using AT89C51low-cost, high accuracy, Micro figures show that the ultrasonic range finder hardware and software design methods. Modular design of the whole circuit from the main program, pre subroutine fired subroutine receive subroutine. display subroutine modules form. SCM comprehensive analysis of the probe signal processing, and the ultrasonic range finder function. On the basis of the overall system design, hardware and software by the end of each module.

　　The research has led to the discovery that the software and hardware designing is justified, the anti-disturbance competence is powerful and the real-time capability is satisfactory and by extension and upgrade, this system can resolve the problem of the car availably, building construction the position of the workplace and some industries spot supervision.

　　　

Key words:AT89C31; Silent Wave；Measure Distance

　　　　　　　　　　　　　　　　　　　　

　　　

　　　目  錄


摘    要···························································I

Abstract··························································II

緒    論···························································1

    I.1   課題設計的目的及其意義·································1

    I.2   超聲波測距系統(tǒng)的設計思路·································1

　　　I.3   課題設計的任務和要求·········································3

1  課題的方案設計與論證···········································4

    1.1   系統(tǒng)整體方案的設計·····································4

    1.2   系統(tǒng)整體方案的論證·····································4

2  系統(tǒng)的硬件結構設計·············································4

    2.1   單片機的功能特點及測距原理·····························5

    2.2   超聲波發(fā)射電路的設..