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基于单片机数字电压表的设计1基于单片机数字电压表的设计目录一设计目的··································································································3二设计要求··································································································3三方案比较与论证······················································································33.1单片机介绍·························································································33.2电源方案····························································································63.3显示方案····························································································63.4AD采样方案························································································73.5键盘部分····························································································7四方案设计····································································································84.1硬件设计····························································································84.2软件设计····························································································9五性能测试·································································································105.1电压测试···························································································105.2电阻值测试························································································115.3短路测试···························································································115.4高压报警测试····················································································115.5串口功能测试····················································································115.6时间功能测试····················································································115.7交流峰峰、周期测试··········································································11结束语············································································································11参考文献·····································································································13附录···············································································································13基于单片机数字电压表的设计2摘要本报告介绍了基于AT89S52单片机为核心的、以AD0809数模转换芯片采样、以1602液晶屏显示的具有电压测量功能的具有一定精度的数字电压表。在实现基础功能要求之上扩展了串口通讯、时钟功能、高压报警、短路测试、电阻测量、交流电压峰峰值和周期测试等功能,使系统达到了良好的设计效果和要求。关键词:AT89S52单片机模数转换液晶显示扩展功能ABSTRACT:ThereportdescribestheAT89S52basedonthemicrocontrollerasthecore,AD0809digital-to-analogconverterchipsampling,to1602LCDdisplaywithvoltagemeasurementfunctionwithacertainprecisionofdigitalvoltagemeter.Inachievingfunctionalrequirementsbasedupontheexpansionofserialcommunications,high-pressurealarm,shortcircuit,electricalresistivitymeasurement,ACvoltageandthepeakofcycletestingandotherfunctions,allowingthesystemtoachievegoodresultsandthedesignrequirements.Keywords:AT89S52SCManalog-to-digitalconversionfunctionsLCDexpansion基于单片机数字电压表的设计3一设计目的自动化专业的专业实践课程。本课程的任务是使学生通过“简易数字电压表的设计”的设计过程,结合所学课程,掌握目前自动化仪表的一般设计过程,锻炼学生的动手能力和分析,解决问题的能力;积累经验,培养按部就班、一丝不苟的工作和对所学知识的综合应用能力。二设计要求1、可以测量0-5V的8路输入电压值;2、可在四位LED数码管上轮流显示或单路选择显示或液晶显示;3、测量最小分辨率为0.019V;4、测量误差约为+0.02V;5、带有一定的扩展功能;6、三方案比较与论证3.1单片机介绍单片机采用AT89S52,它是一个低功耗,高性能CMOS8位单片机,片内含8kBytesISP(In-systemprogrammable)的可反复擦写1000次的Flash只读程序存储器,器件采用ATMEL公司的高密度、非易失性存储技术制造,兼容标准MCS-51指令系统及80C51引脚结构,芯片内集成了通用8位中央处理器和ISPFlash存储单元,功能强大的微型计算机的AT89S52可为许多嵌入式控制应用系统提供高性价比的解决方案。单片机基础电路如下:基于单片机数字电压表的设计4图2单片机基础电路功能特性概述:40个引脚,8kBytesFlash片内程序存储器,256bytes的随机存取数据存储器(RAM),32个外部双向输入/输出(I/O)口,5个中断优先级2层中断嵌套中断,2个16位可编程定时计数器,2个全双工串行通信口,看门狗(WDT)电路,片内时钟振荡器。此外,AT89S52设计和配置了振荡频率可为0Hz并可通过软件设置省电模式。空闲模式下,CPU暂停工作,而RAM定时计数器,串行口,外中断系统可继续工作,掉电模式冻结振荡器而保存RAM的数据,停止芯片其它功能直至外中断激活或硬件复位。同时该芯片还具有PDIP、TQFP和PLCC等三种封装形式,以适应不同产品的需求。引脚功能:·VCC·GND·P0口:P0口是一组8位漏极开路型双向I/O口,也即地址/数据总线复用口。作为输出口用时,每位能吸收电流的方式驱动8个TTL逻辑门电路,对断口P0写“1”时,可作为高阻抗输入端使用。在访问外部数据存储器或程序存储器时,这组端口线分时转换地址(低8位)和数据总线复用,在访问期间激活内部上拉电阻。在FLASH编程时,P0口接收指令字节,而在程序校验时,输出指令字节,校验时,要求外接上拉电阻。·P1口:P1口是一个带内部上拉电阻的8位双向I/O口,P1的输出缓冲级可驱动(吸收或输出电流)4个TTL逻辑门电路。对端口写“1”,通过内部上拉电阻把端口拉到高电平,此时可作输入口。作输入口使用时,因为内部存在上拉电阻,某个引脚被外部信号拉低时会输出一个电流(In)。与AT89C51不同之处是,P1.0和P1.1还可分别作为定时/计数器2的外部计数输入(P1.0/T2)和输入(P1.1/T2EX)。第二功能:P1.0:T2(定时/计数器2外部计数脉冲输入),时钟输出P1.1:T2EX(定时/计数2捕获/重新载触发和方向控制)·P2口:P2是一个带内部上拉电阻的8位双向I/O口,P2的输出缓冲级可驱动(吸收或输出电流)4个TTL逻辑门电路。对端口写“1”,通过内部上拉电阻把端口拉到高电平,此时可作输入口。作输入口使用时,因为内部存在上拉电阻,某个引脚被外部信号拉低时会输出一个电流(IIL)。在访问外部程序存储器或16位地址的外部数据存储器(例如执行MOVX@DPTR指令)时,P2口送出高8位地址数据。在访问8位地址的外部数据存储器(如执行MOVX@RI指令)时,P2口输出P2锁存器的内容。基于单片机数字电压表的设计5·P3口:P3口是一组带有内部上拉电阻的8位双向I/O口。P3口输出缓冲级可驱动(吸收或输出电流)4个TTL逻辑门电路。对P3口写入“1”时,它们被内部上拉电阻拉高并可作为输入端口。此时,被外部拉低的P3口将用上拉电阻输出电流。P3口除了作为一般的I/O口线外,更重要的用途是它的第二功能端口引脚第二功能:P3.0RXDP3.1TXDP3.2INT0(外中断0P3.3INT1(外中断1P3.4TO(定时/计数器0P3.5T1(定时/计数器1P3.6WRP3.7RD·RST:复位输入。当振荡器工作时,RST·ALE/PROG:当访问外部程序存储器或数据存储器时,ALE(地址锁存允许)输出脉冲用于锁存地址的低8位字节。一般情况下,ALE仍以时钟振荡频率的1/6输出固定的脉冲信号,因此它可对外输出时钟或用于定时或用于定时目的。要注意的是:每当访问外部数据存储器时将跳过一个ALE脉冲。如有必要,可通过对特殊功能寄存器(SFR)区中的8EH单元的D0位置位,可禁止ALE操作。该位置位后,只有一条MOVX和MOVC指令才能将ALE激活。此外,该引脚会被微弱拉高,单片机执行外部程序时,应设置ALE·PSEN:程序存储允许PSEN输
本文标题:电子信息工程论文修改稿----简易数字电压表的设计(版本3)
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