目 录
摘 要....................................................................................................................................................................I
Abstract.............................................................................................................................................................II
前 言.................................................................................................................................................................III
第 1 章 方案论证................................................................................................................................................1
1.1
课题设计要求
...........................................................................................................................................1
1.2
方案论证
...................................................................................................................................................1
1.2.1 主控部分的选择................................................................................................................................1
1.2.2 A/D 转换方案....................................................................................................................................3
1.2.3 单片机复位方案................................................................................................................................4
1.2.4 数据显示电路....................................................................................................................................5
1.2.5 LED 显示方案...................................................................................................................................5
1.2.6 量程转换电路....................................................................................................................................6
第 2 章 基于单片机的数字电压表基本原理和组成........................................................................................9
2.1
系统总体设计
...........................................................................................................................................9
2.2
主要芯片介绍
.........................................................................................................................................10
2.2.1 AT89C51 单片机..............................................................................................................................10
2.2.2 ADC0809 芯片介绍.........................................................................................................................13
2.2.3 74LS74 芯片介绍............................................................................................................................16
第 3 章 基于单片机的数字电压表的电路设计..............................................................................................18
3.1
电源设计
.................................................................................................................................................18
3.2
衰减电路设计
.........................................................................................................................................18
3.3
放大电路设计
.........................................................................................................................................19
3.4
单片机最小系统设计
.............................................................................................................................20
3.5
报警电路设计
.........................................................................................................................................21
为了使电压表在使用中能够准确的反应测量情况，给电压表配以报警电路
.
当当前测量电压超量程
测量时系统报警，电压表停止工作。
.......................................................................................................21
3.6 A/D
转换电路设计
..................................................................................................................................21
3.7
开关电路设计
.........................................................................................................................................22
3.8
显示电路设计
.........................................................................................................................................23
3.9
分频电路设计
.........................................................................................................................................24
3.10
硬件整体电路图
...................................................................................................................................25
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