ached)andon-timecontrolproblems;severitygreaterrisk,accordingtotherequiredtroubleshooting,registrationform,andsignedbythoseresponsibleforthesecurityoftheunitforthefirstafterescalation.Thirdarticleopenminemanageroncoalmineproductionjobdistrictwithinofsecurityhiddentroubleshooting,andgovernanceandreportfullisresponsiblefor;securityDeputyManagertieManagerwork,theparagraphconstructionteamheadandthebusinessdepartmentheadMember,andrunmaintenancepersonnel,areshouldaccordingtotheirofdutiesrange,onproductionequipment,andfacilities,andsiteenvironment,aspectsofsecurityhiddenforcheckandreport,andbyhiddenrectificationprogrammeforhiddengovernance.Fourthopen-pitminesafetysectionisresponsibleforthesupervisionandinspectionintheproductionareatroubleshooting,managementandreportingofcomprehensivework.Articlescopeandfocusoftheinspectionpersonnelatvariouslevels:1,operatingpersonnelbeforetakingoverandshiftbeforethejurisdictionareatoconductacomprehensiveinspectionofequipment,runningthesquadlea项目四 电子琴的制作

一、设计目的

通过该设计，掌握8253定时计数的基本原理和应用，掌握8255并行接口芯片的使用，掌握普通键盘的设计，并掌握相应的程序设计和电路设计的技能。是对8253定时计数章节理论学习的总结和补充，为后续的硬件课程的学习打下基础。 二、设计内容

利用KB-C扩展板提供的18个按钮开关，作为电子琴的按键，能够演奏简单的音乐，按键能实现“1-多，2-来，3-米…”，且单个音发音的长短由按键所按下的时间决定，即：某按钮按下时开始发声，松开时结束发音。按钮与8255A的连接见原理部分。其中8255A负责检测按键，8253负责产生各种频率的声音。

三、基本原理

在KB-C板上，端口A负责发按键扫描信息，端口C的低3位，即PC0、PC1、PC2，负责接收扫描结果，如下图所示，先定时通过端口A（PA0，PA1，PA2，PA3，PA4，PA5）扫描各按钮，即先PA0=0，其它为1发信号，然后PA1=0，其它为1…，端口发出1个信号后，即读端口C，如果PC0，PC1，PC2全为高电平，说明无按钮按下，如果PC0为低电平（PC1，PC2肯定为高电平），且此时，端口扫描的情况是：PA0=1，PA1=0，PA2=1，…则说明SW1被按下。

发出各种不同的声音的原理见实验指导书中的音乐发生器实验。

erondutyduringmajorequipmentoverhaul,beforeandaftertheshifttodesignatedstafftounderstandtheoperationofequipmentintheequipmentandcheckonfocus.2,equipmentrepairequipmenttoselectmaintenancecheckatleasttwiceaweektokeyequipmentanddefectivedevicestoincreasethefrequencyofinspection.Teamleaderdedicatedtothedeviceeverydayoperationofalldeviceswithinthescopeofmaintenancepersonnelunderstandthemaintenanceandinspectionofkeyequipment.Paragraph3,theownerandprofessionalandtechnicalpersonnelshouldbecarriedoutdailyafterworksitevisitinspection...Evening.Controlroom:focusedoncoalseamspontaneouscombustionundertroubleshooting,help,landslide,coalfire,earth-moving,roadcarwallsitesafetysupervision,andconscientiouslyimplementtheminerectificationmeasures.Productiontechnologysection:isresponsiblefortroubleshootingwhetherexistsSupercapacity,andSuperached)andon-timecontrolproblems;severitygreaterrisk,accordingtotherequiredtroubleshooting,registrationform,andsignedbythoseresponsibleforthesecurityoftheunitforthefirstafterescalation.Thirdarticleopenminemanageroncoalmineproductionjobdistrictwithinofsecurityhiddentroubleshooting,andgovernanceandreportfullisresponsiblefor;securityDeputyManagertieManagerwork,theparagraphconstructionteamheadandthebusinessdepartmentheadMember,andrunmaintenancepersonnel,areshouldaccordingtotheirofdutiesrange,onproductionequipment,andfacilities,andsiteenvironment,aspectsofsecurityhiddenforcheckandreport,andbyhiddenrectificationprogrammeforhiddengovernance.Fourthopen-pitminesafetysectionisresponsibleforthesupervisionandinspectionintheproductionareatroubleshooting,managementandreportingofcomprehensivework.Articlescopeandfocusoftheinspectionpersonnelatvariouslevels:1,operatingpersonnelbeforetakingoverandshiftbeforethejurisdictionareatoconductacomprehensiveinspectionofequipment,runningthesquadlea

下表为2个八度的音阶表： 音符 频率Hz 音符 频率Hz

四、设计步骤

1.电路设计：根据设计内容，通过分析，设计出相应的电路图。 2、控制字设计：根据要求，设计出各自8255的控制字和8253控制字。 3、程序设计：根据要求，设计程序流程图，并设计相应的程序。 4、验证：在实验室具体测试和验证。

1 ．131 1 262 2 ．147 2 294 3 ．165 3 330 4 ．175 4 349 5 ．196 5 392 6 ．220 6 440 7 ．247 7 494 i 523 实验七 音乐发生器接口实验

一、实验类型

设计性实验（选做）。

二、实验目的和任务

通过音乐发生器实验，学习如何利用8253定时/计数器进行声音控制电路的设计原理与方法。

三、预习要求

预习第7章8253。

四、实验原理

1．音乐发生器驱动模块电路原理如图2.1.12所示。模块包含喇叭SPK，

erondutyduringmajorequipmentoverhaul,beforeandaftertheshifttodesignatedstafftounderstandtheoperationofequipmentintheequipmentandcheckonfocus.2,equipmentrepairequipmenttoselectmaintenancecheckatleasttwiceaweektokeyequipmentanddefectivedevicestoincreasethefrequencyofinspection.Teamleaderdedicatedtothedeviceeverydayoperationofalldeviceswithinthescopeofmaintenancepersonnelunderstandthemaintenanceandinspectionofkeyequipment.Paragraph3,theownerandprofessionalandtechnicalpersonnelshouldbecarriedoutdailyafterworksitevisitinspection...Evening.Controlroom:focusedoncoalseamspontaneouscombustionundertroubleshooting,help,landslide,coalfire,earth-moving,roadcarwallsitesafetysupervision,andconscientiouslyimplementtheminerectificationmeasures.Productiontechnologysection:isresponsiblefortroubleshootingwhetherexistsSupercapacity,andSuperached)andon-timecontrolproblems;severitygreaterrisk,accordingtotherequiredtroubleshooting,registrationform,andsignedbythoseresponsibleforthesecurityoftheunitforthefirstafterescalation.Thirdarticleopenminemanageroncoalmineproductionjobdistrictwithinofsecurityhiddentroubleshooting,andgovernanceandreportfullisresponsiblefor;securityDeputyManagertieManagerwork,theparagraphconstructionteamheadandthebusinessdepartmentheadMember,andrunmaintenancepersonnel,areshouldaccordingtotheirofdutiesrange,onproductionequipment,andfacilities,andsiteenvironment,aspectsofsecurityhiddenforcheckandreport,andbyhiddenrectificationprogrammeforhiddengovernance.Fourthopen-pitminesafetysectionisresponsibleforthesupervisionandinspectionintheproductionareatroubleshooting,managementandreportingofcomprehensivework.Articlescopeandfocusoftheinspectionpersonnelatvariouslevels:1,operatingpersonnelbeforetakingoverandshiftbeforethejurisdictionareatoconductacomprehensiveinspectionofequipment,runningthesquadleaLM386A，74LS08，以及74LS245和LED等。其中LED是配合演奏音乐时产生发光效果而设置的。

50 芯 扩 展 总 线

20 芯 定 时 器 / 并 行 口 插 座

图2.1.12 音乐发生器模块板电路原理框图

2．利用8253控制发声原理与方法的详细阐述，参考计算机接口技术相关参考书.

五、实验仪器与设备

1、MFID微机实验平台，1台 2、PC微机，1台，专用导线， 若干

4、MASM汇编及调试程序（MF开发环境），1套

六、实验内容

基本实验 通过编程使音乐发生器奏出音乐.

利用MFID实验平台和音乐发生器模块进行硬件连接，利用MF2KI集成开发环境进行音乐发生器控制程序设计，调试，直至听到正常的乐曲。

七、实验步骤

1、硬件连线

跳线设置:将电源模块的JP7跳接. 单线连接如右图:

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