单片机原理及应用（双语版·新形态版） 课件 第6章定时器计数器与串行口操作

IntroductoryMicrocontrollerTheoryandApplicationsChapter6Timer/CounterandSerialPortOperation定时COUNTER/TIMEROPERATIONSTART: MOV R0,#0FFhLOOP1: MOV R1,#0C3h DJNZ R1,$ DJNZ R0,LOOP1 RETBusyWaiting计数WhydoweneedaCounter/Timer?HardwarecircuitOscillatorInterruptCPUROMRAMTimer1Timer0I/OportsSerialExternalinterruptsCounterinputsP0P1P2P3TXDRXD8051MicrocontrollerWhatcanwedowithaCounter/Timer?LotsofthingsMeasurethetimeofaneventProduceatimedelayCountitemsWhatisthedifferencebetweenaCounterandTimer?COUNTER/TIMEROPERATIONOSCILLATOR12:101TimerCounterC/Tbit(inTMOD)PinT0COUNTER/TIMEROPERATIONCPUCrystalMachinecyclesClockcyclesT1(16bits)TH1TL1GTFTRC/TTMODTCONINT10=OpenT1Timer1Osc/12C/TP3.5P3.3Counter01TimerStartOverflow0111=Closed40239133843753663573483393210311130122913281427152616251724182319222021P1.0P1.1P1.2P1.3P1.4P1.5P1.6P1.7P2.7P2.6P2.5P2.4P2.3P2.2P2.1P2.0Vcc+5vP0.0P0.1P0.2P0.3P0.4P0.5P0.6VssGNDXTAL2P3.0RXDRSTP3.1TXDP3.2INT0P3.3INT1P3.4T0P3.5T1P3.6WRP3.7RDXTAL1P0.7Vpp/EAPROG/ALEPSEN8051P1P0P2P3DoublefunctionpinsT0TH0TL0T1TH1TL1COUNTER/TIMERSTF1TR1TF0TR0IE1IT1IE0IT0TimerFlag(overflow溢出)TimerRun(Start)COUNTER/TIMERCONTROLTCONregisterTimerFlag(overflow溢出)TimerRun(Start)GATEC/TM1M0GATEC/TM1M0CounterorTimer?TimermodeCOUNTER/TIMERMODESTMODregisterM1M0Mode000011102113Timer1Timer0Notbit-addressableTimerMode0T0TF0flag01FFFh0Interruptsdisabled13-bittimerTR0bit01SETBTR0MOVTH0,#1DhMOVTL0,#57hTimerMode0T0TF0flag011FFFh0Interruptsdisabled13-bittimerTR0bit1TimerMode1T0TF0flag0FFFFh0Interruptsdisabled16-bittimer1SETBTR0MOVTH0,#7DhMOVTL0,#57hTR0bit01TimerMode1T0TF0flag01FFFFh0Interruptsdisabled16-bittimerTR0bit1TL0TimerMode2TH0TF0flag0FFhFFhInterruptsdisabled8-bittimerTR0bitSETBTR0MOVTH0,#43HPreloadvalue01TL0TimerMode2TH0TF0flag01FFhFFhInterruptsdisabled8-bittimerTR0bitPreloadvalue18-bittimerTL0TimerMode2TH0TF0flag01FFhFFhCLRTF0InterruptsdisabledTR0bitPreloadvalue18-bittimerTL0TimerMode2TH0TF0flag01FFhFFhCLRTF0InterruptsdisabledTR0bitPreloadvalue1TH0TimerMode3TL0TF0flag0FFhFFhTwo8-bittimersTR1bit1TR0bit0TF1flag0SETBTR1MOVTL0,#C3hMOVTH0,#63h0TH0TimerMode3TL0TF0flag0FFhFFhTwo8-bittimersTR1bit1TR0bit1TF1flag0SETBTR00TH0TimerMode3TL0TF0flag0FFhFFhTwo8-bittimersTR1bit1TR0bit1TF1flag011IFTimerInterruptisenabledTHEN TF0/TF1flagisclearedautomatically atstartoftheISRIFTimerInterruptisdisabledTHEN TF0/TF1flagmustbeclearedbythe program1.LoadcounterwithpreloadvalueT0TimerMode1(16-bittimer)00TR0TF0Interruptenabled预先加料1.Loadcounterwithpreloadvalue01111111111111110T0FFFBTimerMode1(16-bittimer)00TR0TF0Interruptenabled1.Loadcounterwithpreloadvalue2.StartcounterbysettingTR001111111111111110T0FFFBTimerMode1(16-bittimer)10TR0TF0Interruptenabled1.Loadcounterwithpreloadvalue2.StartcounterbysettingTR001111111111111111T0Timingpulse1FFFB10TR0TF0Interruptenabled1.Loadcounterwithpreloadvalue2.StartcounterbysettingTR001111111111111110T0Timingpulse2FFFC10TR0TF0Interruptenabled1.Loadcounterwithpreloadvalue2.StartcounterbysettingTR011111111111111101T0Timingpulse3FFFD10TR0TF0Interruptenabled1.Loadcounterwithpreloadvalue2.StartcounterbysettingTR011111111111111110T0Timingpulse4FFFE10TR0TF0Interruptenabled1.Loadcounterwithpreloadvalue2.StartcounterbysettingTR011111111111111111T0Timingpulse5FFFF10TR0TF0Interruptenabled1.Loadcounterwithpreloadvalue2.StartcounterbysettingTR03.Onoverflow:TF0isset(inTCON) Interruptgenerated ISRcalled.TFcleared

0000000000000000T0Timingpulse6000011TR0TF0Interruptenabled1.LoadTH0withpreloadvalue(FCh)TH0TimerMode2(8-bitauto-reload)00TR0TF0TL00111111000000000LoadTH0withpreloadvalueStartcounterbysettingTR0TH0TimerMode2(8-bitauto-reload)10TR0TF0TL00111111000000000LoadTH0withpreloadvalueStartcounterbysettingTR0TH0valueisputintoTL0.Starts TL0as8-bitcounterTH0TimerMode2(8-bitauto-reload)10TR0TF0TL01111111001111100LoadTH0withpreloadvalueStartcounterbysettingTR0TH0valueisputintoTL0.Starts TL0as8-bitcounterTH0TimerMode2(8-bitauto-reload)10TR0TF0TL01111111001111101LoadTH0withpreloadvalueStartcounterbysettingTR0TH0valueisputintoTL0.Starts TL0as8-bitcounterTH0TimerMode2(8-bitauto-reload)10TR0TF0TL01111111001111110LoadTH0withpreloadvalueStartcounterbysettingTR0TH0valueisputintoTL0.Starts TL0as8-bitcounterTH0TimerMode2(8-bitauto-reload)10TR0TF0TL01111111001111111LoadTH0withpreloadvalueStartcounterbysettingTR0TH0valueisputintoTL0.Starts TL0as8-bitcounter 4.SetsTF0.CallsISRTH0TimerMode2(8-bitauto-reload)11TR0TF0TL00111111000000000LoadTH0withpreloadvalueStartcounterbysettingTR0TH0valueisputintoTL0.Starts TL0as8-bitcounter 4.SetsTF0.CallsISR 5.Reloads.StartscountingTH0TimerMode2(8-bitauto-reload)10TR0TF0TL01111111001111100TimerInitialisationStepsSettheTimermodeTMODCalculatethepreloadvalue--T0/T1EnabletheinterruptsIEStartthetimerrunningTR0/TR1

6.1.7CalculationofPreloadValuePreloadvalue= Maximumvalue+1–CountvalueModeMaximumPreloadEquation01FFFh(8191)Preloadvalue=8191+1–Countvalue1FFFFh(65535)Preloadvalue=65535+1–Countvalue2FFh(255)Preloadvalue=255+1–Countvalue3FFh(255)Preloadvalue=255+1–CountvalueExample6.1.10.1 AnelectronicpeoplecounterReset8051P1.0LED+5VP0.7T0Counter0125000TimerInitialisationStepsSettheTimermodeTMOD Counter0,Mode1,TMOD=05H2.Calculatethepreloadvalue--T0/T1

3.EnabletheinterruptsIE

4.StartthetimerrunningTR0/TR1

TimerInitialisationStepsSettheTimermodeTMOD Counter0,Mode1,TMOD=05H2.Calculatethepreloadvalue--T0 FE0Ch3.EnabletheinterruptsIE

4.StartthetimerrunningTR0/TR1

PreloadValue=Maximumvalue+1-CountForCount=500Preloadvalue=65535+1–500=FE0ChInitialisationStepsSettheTimermodeTMOD Counter0,Mode1,TMOD=05H2.Calculatethepreloadvalue--T0/T1 FE0Ch3.EnabletheinterruptsIE EA,ET04.StartthetimerrunningTR0/TR1

TR0YNStartEnableinterruptISRReturnReset?InitialisetimerStopcounterLOOP:TurnontheLEDStartcounterTurnofftheLEDReloadthecounter

ORG 0000h SJMP MAIN ;JumpoverISR ORG 000BhAJMP TIMERINTMAIN:MOV P0,#0FFh ;MakeP0input SETB P1.0 ;LEDoff MOV TMOD,#05h ;Counter0,Mode1 SETB EA SETB ET0 ;EnableinterruptsLOOP:MOV TH0,#0FEh MOV TL0,#0Ch ;Loadcounter

SETB TR0 ;StartcounterJNB P0.7,$ ;WaitforReset CLR TR0 ;StopcounterSETB P1.0 ;TurnoffLEDSJMP LOOPTIMERINT: CLR P1.0;TurnonLED MOV TH0,#0FEh MOV TL0,#0Ch;Reloadcounter

RETI

Pleasetrythefollowing.. Question6.3.1 Question6.3.2 Question6.3.17

(Pages132-4)Question6.3.1 PurposeofC/TbitToselectCounter(1)orTimer(0)Question6.3.2WhenisTF0/TF1set?Whencounteroverflows(Maxvalue+1) ORG 0000h AJMP _____ ORG _____ ;Timer0ISR AJMP COUNTMAIN: MOV TMOD,_____ ;Cntr0,Mode1 SETB P1.0 SETB ____ ;Enableints SETB ____ ;EnableCntr0 MOV TH0,_____;Preload MOV TL0,_____ SETB ____ ;StartCountLOOP: NOP ;Mainprog SJMP LOOP COUNT: _____ P1.0 ;ResetP1.0 _____ ;ReturnMAIN000Bh#01hEAET0#0FCh#18hTR0CLRRETIExample6.1.10.2ElectroniccamerashuttercontrolP2.0P3.0ButtonShutter80511=Pressed0=Normal0=Closed1=OpenExample6.1.10.2ElectroniccamerashuttercontrolP2.0P3.0ButtonShutter80510=Normal0=Closed12MHz:1machinecycle=1ms50ms=50000machinecyclesTimerInitialisationStepsSettheTimermodeTMOD Timer1,Mode1,TMOD=10h2.Calculatethepreloadvalue--T1

3.EnabletheinterruptsIE

4.StartthetimerrunningTR0/TR1

C/TM1M0GATEC/TM1M0Timer1Timer0TMODregisterGATE00010000TimerInitialisationStepsSettheTimermodeTMOD Timer1,Mode1,TMOD=10h2.Calculatethepreloadvalue--T0/T1 3CB0h3.EnabletheinterruptsIE

4.StartthetimerrunningTR0/TR1

1machinecycle=1ms50msrequires50000machinecycles

PreloadValue=Maximumvalue+1-CountForCount=50000Preloadvalue=65535+1–50000=3CB0hTimerInitialisationStepsSettheTimermodeTMOD Timer1,Mode1,TMOD=10h2.Calculatethepreloadvalue--T0/T1 3CB0h3.DisabletheinterruptIE ET1=04.StartthetimerrunningTR0/TR1

TR1

BUTTON BIT P2.0 SHUTTER BIT P3.0 ORG 0000H MAIN: SETB BUTTON MOV TMOD,#10h;Timer1,Mode1

CLR TF1REPEAT: MOV TH1,#3Ch MOV TL1,#0B0h;Loadcounter JNB BUTTON,$;Waitforbutton SETB SHUTTER;Openshutter SETB TR1;Starttimer

JNB TF1,$ ;Waitforoverflow CLR TF1 CLR SHUTTER;Closeshutter

JB BUTTON,$;WaitforNormal SJMP REPEATExample6.1.10.3SquarewaveonP3.0.Freq=1kHz;Timer0Mode1;Clock=12MHzP3.080511ms.5msInitialisationStepsSettheTimermodeTMOD Timer0,Mode1,TMOD=01h2.Calculatethepreloadvalue--T0

3.DisabletheinterruptIE

4.StartthetimerrunningTR0

C/TM1M0GATEC/TM1M0Timer1Timer0TMODregisterGATE00010000InitialisationStepsSettheTimermodeTMOD Timer0,Mode1,TMOD=01h2.Calculatethepreloadvalue--T0 FE0Ch3.DisabletheinterruptIE Disableinterrupts4.StartthetimerrunningTR0

SetTR0 1machinecycle=1ms .5msrequires500machinecycles

ForCount=500Preloadvalue=65535+1–500=FE0Ch

WAVE BITP3.0 ORG 0000h MAIN: MOV TMOD,#01h;Timer0,Mode1 CLR TF0;ClearTFflagNEXT: MOV TL0,#0Ch MOV TH0,#0FEh;Preloadtimer

SETB TR0

;Starttimer JNB TF0,$;Awaitoverflow

CLR TR0

;Stoptimer CLR TF0 ;ClearTFflag CPL WAVE;Toggleoutput

SJMP NEXTExample6.1.10.3SquarewaveonP3.0.Freq=1kHz;Timer0Mode1;Clock=12MHzPleasetrythefollowing..Question6.3.7(Pages133)Question6.3.7P0.0Example6.1.10.4TimeforbulletP0.1GunTarget0011Puttimein21h(highbyte)&20h(lowbyte)UseTimer0inMode1.Nointerrupts1machinecycle=1ms8051InitialisationStepsSettheTimermodeTMOD Timer0,Mode1,TMOD=01h2.Calculatethepreloadvalue--T0

3.DisabletheinterruptIE

4.StartthetimerrunningTR0

C/TM1M0GATEC/TM1M0Timer1Timer0TMODregisterGATE00010000InitialisationStepsSettheTimermodeTMOD Timer0,Mode1,TMOD=01h2.Calculatethepreloadvalue--T0 0000h3.DisabletheinterruptIE Disableinterrupts4.StartthetimerrunningTR0

SetTR0 GUN BIT P0.0 TARGET BIT P0.1 ORG 0000h MAIN: MOV P0,#0FFh ;SetP0forinput MOV TMOD,#01h;Timer0,Mode1 MOV TL0,#00h MOV TH0,#00h;Preload=0 JNB GUN,$;WaitforGun SETB TR0;Starttiming

JNB TARGET,$;

WaitforTarget CLR TR0;Stoptimer MOV 21h,TH0 ;Timeinms MOV 20h,TL0 ;inT0

SJMP $GATEC/TM1M0GATEC/TM1M0GATEbitsTimer1Timer0TMODregister6.1.9GATEcontroloftimersTR1bit:Controlbyasoftwareinstructionintheprogram.SETBTR1CLRTR1GATE:ControlbyanexternalvoltageonpinINT0/INT1.StartingandstoppingthetimerT1TH1TL1GTFTRC/T=0TMODTCONINT10=OpenT1Timer1Osc/12C/TP3.5P3.3T1TH1TL1GTFTRC/T=0TMODTCONINT10=OpenT1Timer1Osc/12C/T01P3.5P3.3T1TH1TL1GTFTRC/T=0TMODTCONINT10=OpenT1Timer1Osc/12C/T10INT1*TR1P3.5P3.3IFG=1THENtimerwillrunifTR1*INT1=1(ifbothINT1andTR1arehigh)

IFG=0THENtimerwillrunifTR1=1TR1bit:Controlbyasoftwareinstructionintheprogram.SETBTR1CLRTR1GATE:ControlbyanexternalvoltageonpinINT0/INT1.Startingandstoppingthetimer6.1.10.5Measurethespeedofacar Timer0Mode1.Clock=12MHz6.1.10.5Measurethespeedofacar Timer0Mode1.Clock=12MHzINT08051P3.0Start(1)Stop(0)SSGATEinputPhotocell6.1.10.5Measurethespeedofacar Timer0Mode1.Clock=12MHzINT08051timeINT0P3.0Start(1)Stop(0)SStcartimeINT0GStartStopNotcountingNotcountingCountingGATEinputSettheTimermodeTMOD

Timer0Mode1GATE=12.Calculatethepreloadvalue--T0/T1

3.EnabletheinterruptsIE

4.StartthetimerrunningTR0/TR1

6.1.10.5Measurethespeedofacar Timer0Mode1.Clock=12MHzGATEC/TM1M0GATEC/TM1M0Timer1Timer0TMODregister11006.1.10.5Measurethespeedofacar Timer0Mode1.Clock=12MHz1.SettheTimermodeTMOD

Timer0Mode1GATE=ON,TMOD=09h2.Calculatethepreloadvalue--T0/T1

T0=00003.EnabletheinterruptsIE

ET0=0(Disabled)4.StartthetimerrunningTR0

SetTR0

6.1.10.5Measurethespeedofacar Timer0Mode1.Clock=12MHz SS EQU P3.0 ;Start/stopbutton ORG 0000h MAIN: MOV TMOD,#09h;

Timer0,Mode1 ;GATE=1 MOV TL0,#00h MOV TH0,#00h;

Timer=0000h

JNB SS,$ ;WaitforStart SETB TR0;

Starttimer

JB SS,$ ;WaitforStop

CLR TR0 ;Stoptimer ;T0nowcontainsthevalueoftcar

;inms6.1.10.5Measurethespeedofacar Timer0Mode1.Clock=12MHzPleasetrythefollowing..Question6.3.15Question6.3.16(Page134)Question6.3.15Longestdelay Mode1Clock=11.0592MHzQuestion6.3.16Mode1 Clock=6MHzPreload=03AEhTXRX6.2SERIALDATACOMMUNICATION(RS232Protocol)协议接收发送1101001011010010TXRX110100101101001011110000发送接收LeastSignificantBit最低位MostSignificantBit最高位6.2SERIALDATACOMMUNICATION(RS232Protocol)TXRXParallelCommunication10000111100001111101001011010010HigherspeedMorewiresComplexcircuitboardOnedirectionatonetimeLPTportsoncomputerTXRX1101001011010010SERIALDATACOMMUNICATION(RS232Protocol)11110000发送接收OnewireeachwaySimplecircuitboardBothdirectionsatsametimeSlowspeedCOMportsoncomputerDatabits数据StartbitIdle闲Paritybit校验位StopbitsClock01234567AnRS232Packet

SERIALDATACOMMUNICATION(RS232Protocol)RXDTXDGNDGNDRTSCTSSERIALDATACOMMUNICATIONDB9ConnectorPinsDevice1SERIALDATACOMMUNICATION(RS232Protocol)Device2TXDTXDRXDRXDTheRS232ProtocolLogicLevelTTLvoltageRS232voltage00volts+12volts15volts-12voltsSpeedsoftransmission:-600,1200,2400,4800,9600bits/s (baud)SERIALDATACOMMUNICATION(RS232Protocol)TTLtoRS232converterTTLtoRS232converterLevelConversion:TTLtoRS232(Page129)MAX232+5VTXDTXDRXDRXDTTLRS232++++GNDGND6.2.4TheSerialPortonthe8051SetifTransmitSBUFemptySetifReceiveSBUFhasabyteCPUbusSM0SM1SM2RENTB8RB8TIRISerialControlRegister-SCONTransmitFlag发送标志ReceiveFlag接收标志TheSerialPortonthe8051ModeSelectbitsReceiveENableTheSerialPortonthe8051ModeSM0SM1DescriptionBaudrate000ShiftregisterOsc/121018-bitUARTVariable2109-bitUARTOsc/64Osc/323119-bitUARTVariable通用异步收发器Clock01234567AnRS232Packet

HowdowegeneratetheSerialPortclock?UseTimer1inMode2BaudRateforserialportmode1UseTimer1inMode2.SubroutinetoinitialisetheSerialPort:-INIT: CLR SM0 SETB SM1 ;Setmode1 MOV PCON,#00h;SMOD=0 MOV TH1,#0FDh;9600 SETB REN;RXenable RETTotransmitdatafromA: JNB TI,$;Waitforemptybuffer MOV SBUF,AToreceivedataintoA: JNB RI,$;Waitforbyteinbuffer MOV A,SBUFPollingofSerialPortBusywaitingBusywaiting6.2.11SerialportinterruptflagsRI

- SetwhenabyteisreceivedTI

- Setwhenabytehasbeen transmittedMustbeclearedintheISR6.2.11.2Task:8-bitserialcommunicationat9600baudEachreceivedbyteputinto40hto6Fh.

40h6FhRXD01SBUFRI

ORG 0000h AJMP MAIN ORG 0023hISR_SERIAL: MOV @R0,SBUF INC R0 CJNE R0,#70h,DONE MOV R0,#40hDONE: CLR RI RETIMAIN: _______________ _______________ 6.2.11.2Task:MAIN: MOV R0,#40h ;Startofbuff MOV TMOD,#20h ;T1Mode2 MOV TH1,#0FDh;Baud=9600 SETB EA SETB ES ;Serialinterrupt CL