基于AT89C51的倒车测距报警器的设计 【毕业论文】.doc

毕业设计 基于AT89C51的倒车测距报警器的设计 [摘 要]超声波测距在倒车雷达、液面高度测量等场合有着广泛的应用。本文根据超声波测距离原理，设计了一个简易的超声波倒车测距报警系统。系统主要由控制器模块、超声波收发模块、距离显示模块、声音提示模块、电源模块构成。控制器通过定时器产生周期的脉冲方波信号，经电声转换电路后发出超声波，同时打开定时器计时。声电转换电路将超声波的回波信号转换为电平送单片机中断，根据定时器计得的收发时间差计算障碍物的距离。本设计分析了超声波测距原理，给出了系统的总体设计方案，完成了具体硬件电路图设计以及软件程序设计，最后对系统进行了测试。测试数据表明系统具有较高的精度，较低成本的优点，因此具有一定的实际应用价值。 [关键词]AT89C51；超声波测距；LED数码管显示 Design of the ranging reversing alarm Based on AT89C51 Abstract: There is a wide range of occasions where ultrasonic ranging can be applied, such as in reversing car and liquid level measurement. Based on the ultrasonic distance measurement principle, this paper aims at designing a simple ultrasonic reversing ranging alarm system. The system mainly includes the controller module, ultrasonic receiving module, display module, the voice prompt distance module and power supply module. The controller module generates periodic pulse square wave signal through the timer. Then the conversion circuit emits ultrasonic waves and the timer is opened at the same time. The seismoelectric conversion circuit of the ultrasonic echo signal is converted to a voltage, which is sent to the SCM interrupt port. The SCM calculates the distance of the obstacle according to measured transceiver time difference. This paper analyzes the ultrasonic ranging principle, gives the overall design of the system and completes the concrete hardware circuit design, software program design and the final test of the system. The test data show that the system has higher accuracy together with its low cost. The utility model has a certain practical value. Key words: AT89C51；Ultrasonic Ranging；LED display 目 录 第一章 绪 论 1 1.1 课题研究背景 1 1.2 超声波测距发展历程 1 1.3 超声波测距研究现状 2 1.4 课题主要任务 2 第二章 系统总体设计 3 2.1 设计方案论证 3 2.1.1 控制模块 3 2.1.2 测距模块 3 2.2 系统总体设计方案 4 第三章 系统硬件电路设计 6 3.1 系统主控电路设计 6 3.1.1单片机AT89C51简介 6 3.1.2 时钟电路 9 3.1.3 复位电路 9 3.2 超声波发射与接收电路的设计 10 3.2.1 超声波发射电路的设计 10 3.2.2 超声波接收电路的设计 10 3.3 测距显示电路的设计 11 3.3.1 LED数码管简介 11 3.3.2 LED数码管显示电路的设计 11 3.4 报警电