单片机课程设计报告
题 目：专 业：班 级：姓 名：学 号：指导老师：成 绩：
交通灯控制系统
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目录
前言 ··················································································································· 3 一，任务和要求 ································································································ 3 1.1设计任务 ····································································································· 3 1.2设计要求 ····································································································· 4 1.3设计思路 ····································································································· 4 二，硬件设计 ··································································································· 5 2.1 AT89SC21单片机的概述 ·········································································· 5 2.2 89C51单片机的时钟 ·················································································· 7 2.3 89C51单片机的封装和引脚 ······································································ 8 三，电路模块设计 ·························································································· 10 3.1系统的整体方案设计 ················································································ 10 四，单元电路模块设计 ·················································································· 12 4.1复位电路 ···································································································· 12 4.2晶振电路 ···································································································· 13 4.3倒计时显示电路 ························································································ 14 4.4交通灯电路 ································································································ 15 4.5紧急通行电路 ···························································································· 16 五，系统程序设计 ·························································································· 17 5.1主程序流程图 ···························································································· 17 5.2紧急中断程序流程图 ················································································ 18 5.3程序清单 ···································································································· 18 心得体会 ·········································································································· 22 参考文献
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前言
近年来随着科技的飞速发展，单片机的应用正在不断地走向深入，同时带动传统控制检测日新月益更新。单片机的特点控制功能强抗干扰性强，可靠性高，工作温度范围宽开发周期短，性价比高，易于产品化。交通在人们的日常生活中占有重要的地位，随着人们社会活动的日益频繁，这点更是体现的淋漓尽致。交通信号灯的出现，使交通得以有效管制，对于疏导交通流量、提高道路通行能力，减少交通事故有明显效果。本系统采用单片机AT89C51为中心器件来设计交通灯控制器，系统实用性强、操作简单、扩展性强。本设计就是采用单片机模拟十字路口交通灯的各种状态显示以及倒计时时间。
本设计系统由单片机I/O口扩展系统、交通灯状态显示系统、LED数码显示系统、紧急情况中断系统、复位电路等几大部分组成。系统除基本的交通灯功能外，还具有倒计时、紧急情况处理等功能，较好的模拟实现了十字路口可能出现的状况。
一，任务和要求
1.1设计任务
本设计要求用单片机设计一个智能交通灯控制系统，使其能模仿城市“十字”路口交通灯的功能，并能满足特殊的控制要求（如按键K1、K2、K3的使用），该系统的具体功能如下：
（1） 该控制系统能控制东、西、南、北四个路口的红、黄、绿信号灯正常工作。 （2） 当东西方向准行，南北方向禁行时，东西方向亮绿灯，南北方向亮红灯。 （3） 当南北方向准行，东西方向禁行时，南北方向亮绿灯，东西方向亮红灯。 （4） 两垂直方向的准行时间均为15s。
（5） 准行方向亮绿灯与禁行方向亮红灯10s后，四个道口同时加亮一盏黄灯进
行闪烁，以警告车辆及行人，准行方向与禁行方向即将改变（即准行变为禁行，禁行变为准行）。
（6） 四个道口只用一组由十位和个位组成的数码管显示准行（或禁行）的剩余
时间。
（7） 在交通情况比较特殊的情况下，可以通过K1、K2、K3三个按键对交通灯
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进行控制，具体要实现的功能如下：
当有紧急情况发生，如消防车、救护车等紧急车辆通过时，按下K1键，四个路口同时加亮黄色灯进行闪烁（闪烁时间为5S），并且倒计时显示装置关闭，黄色灯5S闪烁完成后，四个路口的信号灯全部变成红灯，这样四个路口的普通车辆禁行，只允许紧急车辆通过，待紧急车辆通过后。松开K1键，表示紧急状态消除，交通灯控制系统恢复正常工作。 当东西方向车辆过多时，按下K2键，四个路口同时加亮黄灯进行闪烁（闪烁时间为5s），并且倒计时显示装置关闭，黄灯5s闪烁完成后，只允许东西方向车辆通过，南北方向车辆禁行，从而有效地调节东西方向车辆过多的情况，松开K2键，交通灯又开始正常工作。
当南北方向车辆过多时，按下K3键，四个路口同时加亮黄灯进行闪烁（闪烁时间为5s），并且倒计时显示装置关闭，黄灯5s闪烁完成后，只允许南北方向车辆通过，东西方向车辆禁行，从而有效地调节南北方向车辆过多的情况，松开
K3键，交通灯又开始正常工作。 1．2设计要求
（1）十字路口的4个路口都有双色LED（红光，绿光，叠加为黄色光）显示各路口的各条通道的的状态；
（2）每个路口都有两位数码管显示当前红灯的倒计时；
（3）有三种工作状态：正常工作状态，紧急工作状态，设置状态； （4）可利用按键进行改变工作状态； 1.3 设计思路
利用单片机实现交通灯的控制，该任务分以下几个方面：
a 实现红、绿、黄灯的循环控制。要实现此功能需要表示三种不同颜色的LED灯分别接在P1个管脚，用软件实现。
b 用数码管显示倒计时。可以利用动态显示或静态显示，串行并出或者并行并出实现。
C 实现急通车。这需要人工实现，编程时利用到中断才能带到目的，只要有按钮按下，那么四个方向全部显示红灯，禁止以诶车辆通行。当情况解除，让时间回到只能隔断处继续进行。
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总体设计框图
交通灯循环倒最小系统 计时显示 2.1 AT89SC51单片机概述：
AT89SC51是MCS-51系列单片机的典型产品，我们以这一代表性的机型进行系统的讲解。下图是89SC51的基本结构：
定时/计数器、并行接口、串行接口和中断系统等极大单元及数据总线、地址总
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强通车控制 图1-1
二，硬件设计
图2－1 89SC51的基本结构
89SC51单片机包含中央处理器、程序存储器（ROM）、数据存储器（RAM）、