基于单片机的数字频率计设计(创新的自动选当功能) - 毕

四川理工学院毕业设计

基于单片机的数字频率计设计

(创新的自动选当功能)

四川理工学院毕业设计

基于单片机的数字频率计设计

摘 要：一个基于单片机的数字频率计设计，系统硬件主要包括整形电路（由74LS00斯密特触发器组成），分频器74LS161、多路选择器74LS151、与非门74LS00组成的分频模块，控制电路（由AT89C52单片机组成）， LED数码管和显示电路。能根据输入信号自动切换量程，可以测量方波、三角波及正弦波等多种波，结构简单，操作方便，价格低廉，适用于日常生活和生产、计算机、通讯设备、音频视频等科研生产领域。

关键词：单片机；数字频率计；定时器；计数；测量；AT89C52

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四川理工学院毕业设计

Design of digital frequency meter based on single chip

microcomputer

Abstract：The hardware system includes shaping circuit (consisting of 74LS00 Schmitt trigger), frequency module frequency divider 74LS161, 74LS151, 74LS00 MUX NAND gate, control circuit (composed of AT89C52 single chip computer), LED digital tube and display circuit. The software includes control of the main program and interrupt service subroutine, digital transformation procedures and display program. According to the input signal automatic switching range, can be measured in square wave, triangular wave and sine wave, wave, simple structure, convenient operation, low price, suitable for daily life and production, computer, communications equipment, audio video and other fields of scientific research and production.

Keywords: single chip microcomputer; digital frequency meter; timer; counter; measurement; 89C52

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四川理工学院毕业设计

目 录

第1章 引言 .................................................................................................................... 1

1.1 数字频率计的发展和意义 ................................................................................ 1 1.2 数字频率国内外的发展形势 ............................................................................ 1 1.3 本章小结 ............................................................................................................ 2 第2章 系统总体设计 .................................................................................................... 4

2.1 系统设计要求 .................................................................................................... 4 2.2 测频方法 ............................................................................................................ 4 2.3 系统设计思路 .................................................................................................... 5 2.4 系统设计框图 .................................................................................................... 5 2.5 本章小结 ............................................................................................................ 6 第3章 系统硬件设计 .................................................................................................... 7

3.1 单片机模块设计 ................................................................................................ 7

3.1.1 AT89C52介绍 ........................................................................................... 7 3.1.2 单片机引脚分配 .................................................................................... 8 3.1.3 复位电路 .................................................................................................. 8 3.1.4 定时/计数器 ............................................................................................. 9 3.2 电源模块设计 .................................................................................................. 10

3.2.1 电源变压器 ............................................................................................. 11 3.2.2 整流电路 ................................................................................................. 11 3.2.3 滤波电路 ................................................................................................ 12 3.2.4 稳压电路 ................................................................................................ 12 3.2.5 电源模块原理图 .................................................................................... 12 3.3 放大整形模块设计 .......................................................................................... 13

3.3.1 与非门74LS00 ...................................................................................... 13 3.3.2 放大整形模块原理图 ............................................................................ 13 3.4 分频模块设计 .................................................................................................. 14

3.4.1 分频器74LS161芯片 ........................................................................... 15 3.4.2 多路选择器74LS151芯片 ................................................................... 15 3.4.3 分频模块原理图 .................................................................................... 16 3.5 显示电路设计 .................................................................................................. 17

3.5.1 频率数值显示电路 ................................................................................ 18 3.5.2 频率数值单位显示电路 ........................................................................ 18 3.6 整机电路流程 .................................................................................................. 19 3.7 本章小结 .......................................................................................................... 19 第4章 系统软件设计 ................................................................................................. 20

4.1 系统流程图 ...................................................................................................... 21 4.2 初始化 .............................................................................................................. 22 4.3 频率测量模块和量程自动切换模块设计 ...................................................... 22 4.4 显示模块设计 .................................................................................................. 25

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四川理工学院毕业设计

4.5 延时模块设计 .................................................................................................. 28 4.6 本章小结 .......................................................................................................... 28 第5章 系统仿真及数据分析..................................................................................... 29

5.1 电源模块仿真 .................................................................................................. 29 5.2 放大整形电路仿真 .......................................................................................... 29

5.2.1 仿真软件 MULTISIM 10.0仿真整形电路.......................................... 29 5.2.2 仿真放大整形电路 ................................................................................ 30 5.3 频率计仿真 ...................................................................................................... 32

5.3.1 使用KEIL软件编程 ............................................................................. 32 5.3.2 使用软件Proteus仿真频率计 .............................................................. 32 5.4 本章小结 .......................................................................................................... 38 第六章、结论 ............................................................................................................... 39 致谢 ............................................................................................................................... 40 参考文献 ....................................................................................................................... 41 附录1 原理图 .............................................................................................................. 42 附录2 Pcb电路图 ....................................................................................................... 43 附录3 元件清单 .......................................................................................................... 44 附录4 程序源代码 ...................................................................................................... 45 附录5 仿真效果图 ...................................................................................................... 53

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