超声波测距毕业设计.doc

摘 要 本设计介绍了基于单片机控制的超声测距仪的原理：由AT89C51控制定时器产生超声波脉冲并计时，计算超声波自发射至接收的往返时间，从而得到实测距离。并且在数据处理中采用了温度补偿的调整，用四位LED数码管切换显示距离和温度。 整个硬件电路由超声波发射电路、超声波接收电路、电源电路、显示电路等模块组成。各探头的信号经单片机综合分析处理，实现超声波测距仪ABSTRACT The design introduces the principle of the ultrasonic distance measurement instrument based on SCMC-controlled: AT89C51 controls timers to produce the ultrasonic wave pulse and time,count the time of ultrasonic wave spontaneous emission to receive round-trip,thus obtains the measured distance.And the temperature compensation adjustment is used in the data processing, with four LED nixie tubes display distance or temperature by switching. The entire hardware circuit is composed by ultrasonic transmitter circuit, ultrasonic receiver circuit, the power circuit, display circuit, and other modules. The probe signals are integrated analysised by SCMC to achieve the various functions of ultrasonic distance measurement instrument. Based on this has designed systems overall concept, final adoption of hardware and software to achieve the various functional modules. The relevant parts have the hardware schematics and process flow chart.It has given the system constitution, the circuitry and the programming. The instrument system has features: ease of control, stability of operation, highness of precision and distinctness of programme process ,etc. After the realization of the works can be used for needs of the various parameters measured distance applications. Keywords: Ultrasonic wave, Temperature compensation, Measure distance 目 录 摘 要 I ABSTRACT II 1 绪论 1 1.1 课题研究的背景 1 1.2 课题研究的意义 1 1.3 论文结构 2 2 超声波测距原理 3 2.1 超声波简介 3 2.2 超声波测距原理 3 3 方案论证 5 3.1 设计思路 5 3.2 系统结构设计 6 4 主要元件介绍 7 4.1 单片机AT89C51 7 4.2 超声波传感器T40、R40 9 4.3 温度传感器DS18B20 10 5 硬件电路设计 11 5.1 超声波发射电路 11 5.2 超声波接收电路 11 5.3 显示电路 12 5.4 电源电路 12 5.5 复位电路 13 6 软件设计 14 6.1 主程序流程 14 6.2 子程序设计 17 7 软件调试及系统仿真 20 7.1 软件编译调试环境——Keil 20 7.2 Keil工程文件的建立、设置与目标文件的获得 20 7.3 系统仿真环境——Proteus 24 7.4 系统仿真 25 7.5 误差及特性分析 26