单片机试题及答案（single chip examination questions and answers）

单片机试题及答案（SINGLECHIPEXAMINATIONQUESTIONSANDANSWERS）AFILLINTHEBLANKS1POINTSPERMINUTE,20POINTS1MONOLITHICMICROCOMPUTERCONSISTSOFCPU,MEMORYANDTHREEPARTS2,INTHEMCS51SYSTEM,WHENTHESIGNALISVALID,ITMEANSTHATTHESIGNALISSENTOUTSTABLYFROMTHEP0PORT3,ACCESSTO8031PIECESOFEXTERNALDATAMEMORYUSINGTHEADDRESSINGMODE4,ACCUMULATORA80H,EXECUTEINSTRUCTIONADDA,83H,CARRYBITSC5,INSTRUCTIONLCALL37B0H,THEFIRSTADDRESSIN2000H,THECOMPLETIONOFTHEOPERATIONISINTOTHESTACK,SENTTOPC6,MCS51INTERRUPTSOURCE,2INTERRUPTPRIORITY,PRIORITYBYTHESOFTWARETOFILLINTHESPECIALFUNCTIONREGISTERIPTOCHOOSE7,ASSEMBLYLANGUAGEANDTWOBASICINSTRUCTIONSIN8,ADDRESSINGMODE,USINGAASINDEXREGISTERS,ORTOREGISTER9,INTERRUPTREQUESTSIGNALTRIGGERANDTRIGGERTWOTRIGGERMODES10,USETHESERIALPORTEXTENDEDPARALLELPORT,SERIALINTERFACEMODESHOULDBE11,74LS273ISUSUALLYUSEDASASIMPLEINTERFACEEXTENSION,WHILE74LS244ISOFTENUSEDASASIMPLEINTERFACEEXTENSION12,MCS51PARALLELI/OPORTINFORMATIONANDTWOKINDSOFREADINGMETHOD,READMODIFYWRITEOPERATIONISFORPARALLELI/OPORTOFTHELATCH13,THREEIMPORTANTINDEXESOFA/DCONVERTERARE,ANDSUMUPTWO,CHOOSEAQUESTIONCHOOSEACORRECTANSWERFROMTHEALTERNATIVEANSWER,ANDWRITETHECODEINPARENTHESES1POINTSFOREACHQUESTION,10POINTS1THELANGUAGETHATCOMPUTERSCANRECOGNIZEISAASSEMBLYLANGUAGEBNATURALLANGUAGECMACHINELANGUAGECHIGHLEVELLANGUAGE2WHENTHEMCS51CHIPISUSEDTOEXPANDMEMORYCHIPS,THE4I/OPORTSAREUSEDASDATABUSESAP0ANDP2MOUTHBP0MOUTHCP2ANDP3MOUTHDP2MOUTH3,ATLEASTONEOFTHEINTERRUPTSERVICEPROGRAMATRANSFERINSTRUCTIONBTRANSFERINSTRUCTIONCADDITIONINSTRUCTIONDINTERRUPTRETURNINSTRUCTION4THESIGNALTHATDOESNOTWORKWHENACCESSINGEXTERNALMEMORYISABAAALE5,THEFOLLOWINGINSTRUCTIONS,READONLYTHEINSTRUCTIONSOFTHEPINISAMOVP1,ABORLP1,0FHCMOVCC,P15DDJNZP1,LAB6,THEUSEOFTIMERT1,THEREARESEVERALMODESOFWORKA1SPECIESB,2SPECIESC,3SPECIESD,4SPECIES7,IFMCS51INTERRUPTSOURCESAREPROGRAMMEDASTHESAMELEVEL,WHENTHEYSIMULTANEOUSLYAPPLYINTERRUPTS,CPUFIRSTRESPONDSABCT1DT08,WHENTHEMCS51RESPONSEISINTERRUPTED,WHICHOFTHEFOLLOWINGCONDITIONSISNOTNECESSARYTHECURRENTINSTRUCTIONISEXECUTEDB,INTERRUPTISOPENC,NOPEERORADVANCEDINTERRUPTSERVICED,ANDMUSTHAVERETIINSTRUCTION9,IFTHE8255PORTAISSETTOMODE2,THEPORTBISSETTOACANONLYBE0BOR2CEXCEPTFORMODE2,ANDANYOTHERWAYCANDANYWAY10,WHENTHEMCS51MULTIMACHINECOMMUNICATION,SERIALINTERFACEMODESHOULDBEAMODE0BMODE1CMODE2DMODE0ORMODE2FOURREADORWRITEPROGRAMS15POINTS1WRITEAPROGRAMTOTRANSFERTHEDATAFROMTHE100UNITSOFTHE1000HUNITTOTHEBEGINNINGOFTHE2000H8POINTS2SETR020H,R125H,20H80H,21H90H,22HA0H,25HA0H,26H6FH,27HAFTERTHEFOLLOWINGPROGRAMISEXECUTED,WHATISTHERESULT20H21H22H23HCYR0R1CLRCMOVR2，3环MOVA，R0ADDCA，R1MOVR0，一INCR0公司R1DJNZR2，环JNC下MOVR0，01H否则，下一步DECR0否则，五、MCS51单片机外扩展一片2716存储器，画出系统电路原理图，写出地址分布。（15分）六、MCS51单片机P1端口上，经驱动器接有只发光二极管FOSC8，6MHZ，试编写程序，使这8只发光管每隔2秒循环发光。（20分）单片微机原理及应用一卷参考答案一、填空题（每空1分，共20分）1、I/O2、低83415位地址、寄存器间接、2003H，37B06、5个，IP7、符号指令和伪指令8、PC或DPTR9、电平和脉冲10、方式011、输出输入12、读引脚和读锁存器13、转换速度、分辨率和转换精度。二、选择题（从备选答案中选择一个正确答案，并将代号写在括号内。每题1。分，共10分）1，C2，B3，D4，C5，C6，C7，B8，C9，A10，C三、简答题（每题5分，共20分）1、MCS51单片机内部包括哪些主要逻辑功能部件答MCS51单片机主要由下列部件组成1个8位CPU；1个片内振荡器及时钟电路；4KBROM程序存储器，256BRAM；21个特殊功能寄存器；2个16位定时/计数器；4个8位并行I/O口及1个可编程全双工串行接口；可寻址64KB的外部程序存储器空间；可寻址64KB的外部数据存储器空间；5个中断源、两个优先级中断嵌套中断结构。2、MCS51单片机内部有几个定时/计数器它们由哪些寄存器组成答MCS51单片机内部有两个16位可编程的定时/计数器，简称定时器0（T0）和定时器1（T1）。它们分别由方式寄存器TMOD、控制寄存器TCON和数据寄存器TH0、TL0，TH1、TL1组成。3、单片机对中断优先级的处理原则是什么答（1）低优先级中断源可被高优先级中断源所中断，而高优先级中断源不能被任何中断源所中断；（2）一种中断源（不管是高优先级还是低优先级）一旦得到响应，与它同级的中断源不能再中断它。当同时收到几个同一优先级的中断时，响应哪一个中断源取决于内部查询顺序。其优先级排列如下中断源同级内的中断优先级0最高外部中断定时器/计数器0溢出中断外部中断1定时器/计数器1溢出中断串行口中断最低4、设MCS51单片机的FOSC12MHZ，要求用T0定时150US，分别采用定时方式0，定时方式1和方式2时的定时初值。采用方式0定时的初值为FBH，50H采用方式1定时的初值为FFH，6AH采用方式2定时的初值为6AH四、阅读或编写程序1、编写一程序实现将1000H单元开始的100个单元的数据转移到2000H开始的单元中。（8分）程序如下ORG0000HMOVDPTR，1000H；给源数据块地址指针DPTR赋初值MOVP2，20H；给目的数据块地址指针P2和R0赋初值MOVR0，00H环MOVX指令，指令MOVXR0，一INCDPTRINCR0CJNER0，64H，环否则，2、设R020H，R125H20H90H80H,21H,22HA0H,25HA0H,26H6FH,27H,AFTERTHEFOLLOWINGPROGRAMISEXECUTED,WHATISTHERESULT7POINTS20H21H20H00H22H23H17H01HCYA128H17HR023HR1CLRCMOVR2,3ONERINGMOV,R0ADDCAR1MOVR0,ACOMPANYR0COMPANYR1DJNZR2,RINGAJNCMOVR0,01HSJMPDOLLARSNEXTMONTH,R0SJMPDOLLARSFIVE,MCS51SINGLECHIPMICROCOMPUTERTOEXPANDAPIECEOF2716MEMORY,DRAWTHESYSTEMCIRCUITSCHEMATICDIAGRAM,WRITEADDRESSDISTRIBUTION15POINTSTHEADDRESSRANGEOFPROGRAMMEMORYIS0000H07FFH,0800H0FFFH,1000H17FFHSIX,MCS51SINGLECHIPP1PORT,THEDRIVERCONNECTEDWITH8LIGHTEMITTINGDIODES,FOSC6MHZ,TRYTOWRITEPROCEDURES,SOTHATTHE8LIGHTEMITTINGDIODESEVERY2SECONDSCYCLEOFLIGHT20POINTSMOVTMOD,10MOVJAN,OD8HMOVTL1,0E0HSETBTR1MOV,80HAG1MOVP1,AMOVR7,100AG2JBCTF1,AG3SJMPAG2AG3MOVJANUARY,OD8HMOVTL1,0E0HDJNZR7,AG2RRASJMPAG1BONE,ONE,FILLINTHEBLANKS1POINTSPERMINUTE,20POINTS1THESYSTEMBUSOFTHECOMPUTERHASADDRESSBUS,CONTROLBUSAND2USUALLY,THEPCSP,ONTHEPOWERONRESETOFTHESINGLECHIPMICROCOMPUTER,WHILETHEWORKINGREGISTERDEFAULTSTOGROUPONE,ANDTHEADDRESSRANGEOFTHEREGISTERISFROMTHEOPCODEADDRESSIS1000H3,JZE,E20H,ANDTHEDESTINATIONADDRESSOFITIS4,ASSEMBLYLANGUAGECANUSEPSEUDOINSTRUCTIONS,THEYARENOTREALINSTRUCTIONS,BUTONLYFORSOMEKINDOFCONTROL5,ASSUMETHECONTENTSOFTHEACCUMULATOR30HA,EXECUTEINSTRUCTIONS1000HMOVCAA,PCAFTERTHAT,THECONTENTSOFTHEPROGRAMMEMORYUNITARESENTTOTHEACCUMULATORA6,MCS51SINGLECHIPMICROCOMPUTERACCESSTOEXTERNALMEMORY,THEUSEOFSIGNALLATCHFROMTHEMOUTHOFTHELOW8BITADDRESSSIGNAL7,MCS51MICROCONTROLLER8031HASABITTIMER/COUNTER,CANBESETTOWORKINAWAY8,MCS51SINGLECHIPMICROCOMPUTERHASAINTERRUPTSOURCE,CANBEDIVIDEDINTOINTERRUPTPRIORITYPOWERUPRESET,INTERRUPTSOURCEINTERRUPTLEVELISTHEHIGHEST9,USETHESERIALPORTEXTENDEDPARALLELPORT,SERIALINTERFACEMODESHOULDBE10THETWOMOSTIMPORTANTINDEXESOFSEMICONDUCTORMEMORYARESUM11IFTHEOUTPUTVOLTAGEOFA8BITD/ACONVERTERIS5V,THERESOLUTIONOFTHED/ACONVERTERISASFOLLOWS12,WHENWRITINGTHE8255ACONTROLWORD,YOUNEEDTOSETA1ANDA0ASTWO,CHOOSEAQUESTIONCHOOSEACORRECTANSWERFROMTHEALTERNATIVEANSWER,ANDWRITETHECODEINPARENTHESESEACHITEMIS1POINTS,ATOTALOF10POINTS1INCPU,SOMEOFTHECHARACTERISTICREGISTERSTHATREFLECTTHESTATEOFTHEPROGRAMORREFLECTTHERESULTSOFTHEOPERATIONARE1PSWPCBCDSP2,TOVISITTHEMCS51CHIPRAMTRANSFERINSTRUCTIONOPCODEMNEMONICINSTRUCTIONITIS1MOVMOVXBCDABOVEISMOVC3THEJUMPRANGEOFINSTRUCTIONALMPIS1256B1KBBCD64KB2KB4,TOENABLEMCS51TORESPONDTOTHETIMERT1INTERRUPT,THESERIALINTERFACEINTERRUPT,ITSINTERRUPTALLOWSREGISTERIECONTENTSHOULDBE198H84HBCD22H42H5INTERRUPTREQUESTSIGNALSISSUEDBYEACHINTERRUPTSOURCEARERECORDEDINTHEMCS51SYSTEM1IEIPBCDSCONTCON6,CPUADDRESSINGPERIPHERALSPORTADDRESSTWOWAYS,ONEISTHEUNIFIEDADDRESSING,ANDTHEOTHERISAHYBRIDADDRESSINGBDYNAMICADDRESSINGCINDEPENDENTADDRESSINGDINDEXEDADDRESSING7INTHEFOLLOWINGFOURNARRATIVES,ONEOFTHEMISTAKESISATHEADDRESSSPACEOF16ADDRESSLINESISUPTO1MBBTHESTORAGEUNITOFTHEMEMORYISBYTEADDRESSABLECTHEREGISTERUSEDTOSTOREADDRESSINCPUISCALLEDADDRESSREGISTERDONLYADDRESSINFORMATIONCANBETRANSMITTEDOVERTHEADDRESSBUS8,WHENMCS51EXPANDSA8255,ITNEEDSTOOCCUPYPORTADDRESSA1B2C3D49,WHENTHEMCS51PORTISUSEDTOEXTENDTHEPARALLELI/OPORT,THESERIALPORTSHOULDBESELECTEDAMODE0BMODE1CMODE2DMODE310,AMEMORYCHIPISA8KB4/CHIP,THENTHEROOTOFITSADDRESSLINEISA11ROOTSB,12ROOTSC,13ROOTSD,14ROOTSFOURREADORWRITEPROGRAMS15POINTS1READTHEFOLLOWINGPARAGRAPHSANDANSWERTHEQUESTIONS1WHATKINDOFOPERATIONDOESTHEPROGRAMPERFORM2,THEKNOWNINITIALVALUE60H23H,61H61H,ANDAFTERTHEPROGRAM62HCLRCMOVA,9AHSUBBA,60HADDA,61HDAAMOV62H,A2WRITEAPROGRAMTOCLEARALLTHE7000H70FFHUNITSINTHEOUTOFDATEDATAMEMORY8POINTSFIVE,MCS51MICROCONTROLLEREXPANSIONOFAPIECEOF8255,DRAWTHESYSTEMCIRCUITSCHEMATICS,WRITEADDRESSDISTRIBUTION15POINTSSIX,MCS51MICROCONTROLLERP1PORT,THEDRIVERCONNECTEDWITH8LIGHTEMITTINGDIODES,FOSC6MHZ,TRYTOWRITEPROCEDURES,SOTHATTHE8LIGHTEMITTINGDIODESEVERY2SECONDSCYCLEOFLIGHT20POINTS“SINGLECHIPMICROCOMPUTERPRINCIPLEANDAPPLICATION“EXAMINATIONPAPERBREFERENCEANSWERSFIRST,FILLINTHEBLANKS1POINTSPERMINUTE,20POINTS1,DATABUS2,PC0000H,SP07H0000H07H3,1022H4,ASSEMBLYPROCESSFORSOMEKINDOFCONTROL5,1031H6,ALE,P07,216,FOUR,8,5,2EXTERNALINTERRUPT09,MODE010,STORAGECAPACITYANDSTORAGESPEED11,5/25500196V12,11TWO,CHOOSEAQUESTIONCHOOSEACORRECTANSWERFROMTHEALTERNATIVEANSWER,ANDWRITETHECODEINPARENTHESES1POINTSFOREACHQUESTION,10POINTS1,B2,B3,C4,A5,B6,C7,A8,D9,A10,CTHREE,QUESTIONSANDANSWERS5POINTS,20POINTSEACH1WHATISTHERELATIONSHIPBETWEENTHECLOCKCYCLEANDTHEOSCILLATIONPERIODOFMCS51MICROCONTROLLERHOWTODIVIDETHETIMESEQUENCEOFAMACHINECYCLEANSWERCLOCKCYCLEISTHEMOSTBASICUNITOFTIMEOFSCMTHEMACHINECYCLEISTHETIMEREQUIREDTOCOMPLETEASPECIFIEDOPERATIONAMACHINECYCLEIS6CLOCKCYCLES,ATOTALOF12OSCILLATIONPERIODICITY,INTURNEXPRESSEDASS1P1,S1P2,S6P1,S6P22WHATARETHESIMILARITIESANDDIFFERENCESBETWEENTHEFOURPARALLELI/OPORTSWITHINMCS51WHATISTHEFUNCTIONATHEMCS51MICROCONTROLLERHASFOUR8BITBIDIRECTIONALPARALLELI/OPORTS,EACHOFWHICHCONSISTSOFALATCH,ANOUTPUTDRIVERANDANINPUTBUFFERBUTTHEFOURFUNCTIONSOFTHEPORTARENOTALLTHESAME,THEP0PORTCANBEUSEDASAGENERALI/OPORT,BUTALSOCANBEUSEDASADDRESS/DATABUSP1PORTISAQUASIBIDIRECTIONALPARALLELPORT,ASAGENERALPARALLELI/OPORTTOUSEINADDITIONTOP2CANBEUSEDASAUNIVERSALI/OUSE,CANALSOACCESSTHEEXTERNALMEMORYINCPUHIGHEIGHTADDRESSLINESP3ISAMULTIFUNCTIONALPORTINADDITIONTOAQUASIBIDIRECTIONALI/OFUNCTION,BUTALSOHASSECONDFUNCTIONS3BRIEFLYDESCRIBETHEINTERRUPTRESPONSEPROCESSOFMCS51SINGLECHIPMICROCOMPUTERANSWERCPUSEQUENTIALLYSAMPLESEACHINTERRUPTSOURCEDURINGEACHS5P2OFTHEMACHINECYCLE,ANDCHECKSTHEINTERRUPTFLAGINTHEORDEROFPRIORITYINTHENEXTMACHINECYCLES6INTERVAL,SUCHASTHEQUERYTOANINTERRUPTFLAGIS1,THEINTERRUPTWILLBEPROCESSEDBYPRIORITYINTHENEXTMACHINECYCLES1,ANDTHEINTERRUPTSYSTEMWILLAUTOMATICALLYSENDTHECORRESPONDINGINTERRUPTVECTORADDRESSTOTHEPCTHROUGHTHEHARDWARE,SOASTOENTERTHECORRESPONDINGINTERRUPTSERVICEPROGRAMONCETHEINTERRUPT,CPUFIRSTSETTHECORRESPONDINGINTERRUPTPRIORITYTRIGGER“,ANDTHENBYTHEHARDWAREIMPLEMENTATIONOFALONGCALLINSTRUCTION,THECURRENTPCVALUEINTOTHESTACK,INORDERTOPROTECTTHEENTRANCEADDRESSBREAKPOINT,ANDTHENTHERESPECTIVEINTERRUPTSERVICEINTOPC,ANDTHENFROMTHECPUINTERRUPTSERVICEPROGRAMSTARTSTOEXECUTEFORSOMEINTERRUPTSOURCES,CPUAUTOMATICALLYCLEARSTHEINTERRUPTFLAGAFTERTHERESPONSEISINTERRUPTEDWHATISTHEFUNCTIONOFTHESAMPLEANDHOLDCIRCUITIN4ANDA/DCONVERSIONINTERFACEWHATARETHEPRECONDITIONSFOROMITTINGTHESAMPLEANDHOLDCIRCUITANSWERTHEFUNCTIONOFTHESAMPLEANDHOLDCIRCUITINTHEA/DCONVERSIONINTERFACEISTOCONVERTATIMEEDGESIGNALINTOATIMEDISCRETESIGNAL,AN