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HT46R068B Fiches technique(PDF) 61 Page - Holtek Semiconductor Inc |
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HT46R068B Fiches technique(HTML) 61 Page - Holtek Semiconductor Inc |
61 / 135 page Rev. 1.50 60 �e���a�� 05� �015 Rev. 1.50 61 �e���a�� 05� �015 HT46R068B/HT46R069B Enhanced A/D 8-Bit OTP MCU HT46R068B/HT46R069B Enhanced A/D 8-Bit OTP MCU Ti me r Ov er fl ow PF D Cl oc k PA 1 Da ta PF D Ou t put a t PA 1 PFD Function I/O Interfacing TheTimer/EventCounter,whenconfiguredtorunintheeventcounterorpulsewidthcapture mode,requirestheuseofanexternaltimerpinforitsoperation.Asthispinisasharedpinitmust beconfiguredcorrectlytoensurethatitissetupforuseasaTimer/EventCounterinputpin.Thisis achievedbyensuringthatthemodeselectbitsintheTimer/EventCountercontrolregister,selecteither theeventcounterorpulsewidthcapturemode.AdditionallythecorrespondingPortControlRegister bitmustbesethightoensurethatthepinissetupasaninput.Anypull-highresistorconnectedtothis pinwillremainvalidevenifthepinisusedasaTimer/EventCounterinput. Programming Considerations Whenconfiguredtoruninthetimermode,theinternalsystemclockisusedasthetimerclocksource andisthereforesynchronisedwiththeoveralloperationofthemicrocontroller.Inthismodewhen theappropriatetimerregisterisfull,themicrocontrollerwillgenerateaninternalinterruptsignal directingtheprogramflowtotherespectiveinternalinterruptvector.Forthepulsewidthcapturemode, theinternalsystemclockisalsousedasthetimerclocksourcebutthetimerwillonlyrunwhenthe correctlogicconditionappearsontheexternaltimerinputpin.Asthisisanexternaleventandnot synchronisedwiththeinternaltimerclock,themicrocontrollerwillonlyseethisexternaleventwhen thenexttimerclockpulsearrives.Asaresult,theremaybesmalldifferencesinmeasuredvalues requiringprogrammerstotakethisintoaccountduringprogramming.Thesameappliesifthetimeris configuredtobeintheeventcountingmode,whichagainisanexternaleventandnotsynchronised withtheinternalsystemortimerclock. WhentheTimer/EventCounterisread,orifdataiswrittentothepreloadregister,theclockisinhibited toavoiderrors,howeverasthismayresultinacountingerror,thisshouldbetakenintoaccountbythe programmer.Caremustbetakentoensurethatthetimersareproperlyinitialisedbeforeusingthem forthefirsttime.Theassociatedtimerenablebitsintheinterruptcontrolregistermustbeproperlyset otherwisetheinternalinterruptassociatedwiththetimerwillremaininactive.Theedgeselect,timer modeandclocksourcecontrolbitsintimercontrolregistermustalsobecorrectlysettoensurethe timerisproperlyconfiguredfortherequiredapplication.Itisalsoimportanttoensurethataninitial valueisfirstloadedintothetimerregistersbeforethetimerisswitchedon;thisisbecauseafterpower- ontheinitialvaluesofthetimerregistersareunknown.Afterthetimerhasbeeninitialisedthetimercan beturnedonandoffbycontrollingtheenablebitinthetimercontrolregister. WhentheTimer/EventCounteroverflows,itscorrespondinginterruptrequestflagintheinterrupt controlregisterwillbeset.IftheTimer/EventCounterinterruptisenabledthiswillinturngenerate aninterruptsignal.Howeverirrespectiveofwhethertheinterruptsareenabledornot,aTimer/Event Counteroverflowwillalsogenerateawake-upsignalifthedeviceisinaPower-downcondition. ThissituationmayoccuriftheTimer/EventCounterisintheEventCountingModeandifthe externalsignalcontinuestochangestate.Insuchacase,theTimer/EventCounterwillcontinueto counttheseexternaleventsandifanoverflowoccursthedevicewillbewokenupfromitsPower- downcondition.Topreventsuchawake-upfromoccurring,thetimerinterruptrequestflagshould firstbesethighbeforeissuingthe"HALT"instructiontoentertheIdle/SleepMode. |
Numéro de pièce similaire - HT46R068B_15 |
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Description similaire - HT46R068B_15 |
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