武汉理工大学华夏学院《微机原理与接口技术》课程设计
华夏学院
《微机原理与接口技术》课程设计
题 目:
倒 计 时 器
学院(系): 信息工程系
年级专业:
自动化 1082 班
学
号:
10212408221
学生姓名:
林 庆 祥
指导教师:
李 文 彦
武汉理工大学华夏学院《微机原理与接口技术》课程设计
课程设计任务
学生姓名: 林 庆 祥
专业班级: 自动化 1082
指导教师: 李 文 彦
工作单位: 华夏学院
题 目: 倒计时器设计
初始条件:
1. 运用所学的微机原理知识;
2. 微机原理实验室的实验箱设备。
要求完成的主要任务: (包括课程设计工作量及其技术要求,以及说明
书撰写等具体要求)
1. 电路具有时间显示功能,要求用 1 位七段数码管;
2. 要求电路为 9 秒递减计时,每隔 1 秒钟,计时器减 1;
3. 要有外部开关,控制计数器的直接清零、启动和暂停/连续计时功能;
4. 当计时器倒计时为零时,即定时时间到,显示为零,同时发出声光
报警信号。
5. 严格按照课程设计说明书要求撰写课程设计说明书。
时间安排:
序号
阶 段 内 容
1 设计思路、原理电路设计
2 编程,调试
3 撰写课程设计报告
计
合
所需时间
(天)
1
3
1
5
指导教师签名:
系主任(或责任教师)签名:
年
年
月 日
月 日
武汉理工大学华夏学院《微机原理与接口技术》课程设计
摘要
本课程设计的主要目的是提高实践能力,包括提高汇编等语言的编程能力
及对接口等硬件的理解分析能力和设计接口电路的能力,从而学以致用。只有通
过实际编程和微机接口的硬件实践,才能真正掌握软硬件设计的方法,从中得到
收益和提高。
此次课程设计我做的是一个倒计时器设计,所用到的主要芯片是 8255,用
8255 芯片当中的 A、B、C 三端口,A、B 两端口均采用方式一基本输入输出,其
中,C 口用于输入,AB 口用于输出。用试验箱上的三个开关来控制 C 口的状态,
B 口的输出接到试验箱上的数码管,A 口接试验箱上的报警器和彩灯。
此次设计我做了倒计时的 10 种变化模式,即从 9 降到 0,有外部开关能控
制其暂停、复位,在倒计时为零 0 时发出声光警报。。
其中涉及到的延时我采用的是循环,进出栈的方式。
关键字:汇编语言 8255 芯片 倒计时 控制 循环 延时
武汉理工大学华夏学院《微机原理与接口技术》课程设计
目 录
前 言 ··················································································································· 1
第一章 倒计时方案设计 ······················································································· 2
1、设计要求··············································································································2
2、设计方案确定······································································································2
第二章 8255 芯片介绍 ·························································································· 3
1、8255 内部结构及引脚·························································································3
2、8255 端口地址·····································································································4
第三章 模块设计 ···································································································5
1、显示模块··············································································································5
2、控制模块··············································································································5
3、报警亮灯模块······································································································6
4、延时等待模块······································································································6
第四章 软件设计 ···································································································7
1、主程序框图··········································································································7
2、源程序设计··········································································································7
3、总程序整理··········································································································7
第五章 安装调试 ···································································································9
1、软件调试··············································································································9
2、调试过程··············································································································9
小 结 ··················································································································10
参考文献 ··············································································································11
附录:
源程序···························································································· 12
硬件连接图······················································································ 14
本科生课程设计成绩评定表·································································15
武汉理工大学华夏学院《微机原理与接口技术》课程设计
前 言
本学期学习了微机计算机原理与接口技术课程,初步了解了汇编语言和微
机的内部结构。当然课堂上学习的只是理论知识,课堂教学的实验也只是很简单
的没有系统的让我们去学会做一个有关微机的汇编设计本课程设计的主要目的
是提高实践能力,包括提高汇编等语言的编程能力及对接口等硬件的理解分析能
力和设计接口电路的能力,从而学以致用。只有通过实际编程和微机接口的硬件
实践,才能真正掌握软硬件设计的方法,从中得到收益和提高。
通过这种设计课程,我们一方面可以结合课程的教学内容循序渐进地进行
设计方面的实践训练,另一方面,在参与一系列子项目的实践过程中,还能提高
如何综合运用所学知识解决实际问题的能力,以及获得有关项目管理和团队合作
等等众多方面的具体经验,增强对相关课程具体内容的理解和掌握能力,培养对
整体课程知识综合运用和融会贯通能力。
最后,向此次课程设计的指导老师李文彦老师以及在课程设计中帮助、支
持我的同学表示衷心的感谢。由于本次课程设计时间仓促且自己水平有限,难免
还存在一些错误和不妥之处,恳请老师批评指正。
4
武汉理工大学华夏学院《微机原理与接口技术》课程设计
第一章 倒计时设计方案
1、设计要求
(1)电路具有时间显示功能,要求用 1 位七段数码管;
(2)要求电路为 9 秒递减计时,每隔 1 秒钟,计时器减 1;
(3)要有外部开关,控制计数器的直接清零、启动和暂停/连续计时功能;
(4)当计时器倒计时为零时,即定时时间到,显示为零,同时发出声光报警
信号。
2、方案确定
考虑各方因素,因为本次课程设计所提供的实验箱上 8253 只提供了一个工作
通道,实验箱上所给的标准脉冲为 1.8M。这样在通过 8253 分频后最小只能提供
F=1.8M/65535=27HZ,这样就只能在软件中在通过延时程序来达到 1HZ 的脉冲,
这种情况下 8253 的使用就没有走时准确的优势,故舍弃 8253。用 8255 达到课
程设计要求并且成本最低,所以确定以 8255 来设计。
芯片只选择 8255A,使用软件延时,在程序中使用延时语句来输出秒脉冲,
使用 8255A 作为输入/输出接口。采用在软件中控制循环程序的方式来控制倒计
时的复位/暂停。此方案性价比最高,但是相应的由于使用了软件延时,因为芯
片损耗以及芯片在工作时间过长后走时会不够准确。
5
武汉理工大学华夏学院《微机原理与接口技术》课程设计
第二章 8255A 芯片介绍
1、8255 芯片的内部结构及引脚
8255 可编程外围接口芯片是 Intel 公司生产的通用并行 I/O 接口芯片,它
具有 A、B、C 三个并行接口,用+5V 单电源供电,能在以下三种工作方式下工作:
方式 0—基本输入/输出方式
方式 1—选通输入/输出方式
方式 2—双向选通输入/输出方式
8255 内部结构框图如图 3.1 所示:
图 3.1 8255 内部结构框图
8255 引脚图如图 3.2 所示,各引脚功能如下:
D7~D0——与 CPU 侧连接的八条双向数据线;
WR(低电平有效)——写输入信号;
RD(低电平有效)——读输入信号;
CS(低电平有效)——片选输入信号;
A0、A1——片内寄存器选择输入信号;
PA7~PA0——A 口外设双向数据线;
6
武汉理工大学华夏学院《微机原理与接口技术》课程设计
PB7~PB0——B 口外设双向数据线;
PC7~PC0——C 口外设双向数据线;
RESET——复位输入信号
图 3.2 8255 引脚图
2、8255 端口地址
表 3.1
8255 端口地址表
端口
PA 口
PB 口
PC 口
控制口
地址
60H
61H
62H
63H
7