HT68F005 datasheet(72/93 Pages) HOLTEK

72 / 93 page

Rev. 1.00

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HT68F005/HT68F006

Enhanced I/O Flash Type MCU

HT68F005/HT68F006

Enhanced I/O Flash Type MCU

Interrupt Operation

Whentheconditionsforaninterrupteventoccur,suchasaTMComparatorPorComparatorA

match,etc.,therelevantinterruptrequestflagwillbeset.Whethertherequestflagactuallygenerates

aprogramjumptotherelevantinterruptvectorisdeterminedbytheconditionoftheinterruptenable

bit.Iftheenablebitissethighthentheprogramwilljumptoitsrelevantvector;iftheenablebitis

zerothenalthoughtheinterruptrequestflagissetanactualinterruptwillnotbegeneratedandthe

programwillnotjumptotherelevantinterruptvector.Theglobalinterruptenablebit,ifclearedto

zero,willdisableallinterrupts.

Whenaninterruptisgenerated,theProgramCounter,whichstorestheaddressofthenextinstruction

tobeexecuted,willbetransferredontothestack.TheProgramCounterwillthenbeloadedwitha

newaddresswhichwillbethevalueofthecorrespondinginterruptvector.Themicrocontrollerwill

thenfetchitsnextinstructionfromthisinterruptvector.Theinstructionatthisvectorwillusually

bea“JMP”whichwilljumptoanothersectionofprogramwhichisknownastheinterruptservice

routine.Hereislocatedthecodetocontroltheappropriateinterrupt.Theinterruptserviceroutine

mustbeterminatedwitha“RETI”,whichretrievestheoriginalProgramCounteraddressfrom

thestackandallowsthemicrocontrollertocontinuewithnormalexecutionatthepointwherethe

interruptoccurred.

Thevariousinterruptenablebits,togetherwiththeirassociatedrequestflags,areshowninthe

accompanyingdiagramswiththeirorderofpriority.Someinterruptsourceshavetheirown

individualvectorwhileotherssharethesamemulti-functioninterruptvector.Onceaninterrupt

subroutineisserviced,alltheotherinterruptswillbeblocked,astheglobalinterruptenablebit,

EMIbitwillbeclearedautomatically.Thiswillpreventanyfurtherinterruptnestingfromoccurring.

However,ifotherinterruptrequestsoccurduringthisinterval,althoughtheinterruptwillnotbe

immediatelyserviced,therequestflagwillstillberecorded.

Ifaninterruptrequiresimmediateservicingwhiletheprogramisalreadyinanotherinterruptservice

routine,theEMIbitshouldbesetafterenteringtheroutine,toallowinterruptnesting.Ifthestack

isfull,theinterruptrequestwillnotbeacknowledged,eveniftherelatedinterruptisenabled,until

theStackPointerisdecremented.Ifimmediateserviceisdesired,thestackmustbepreventedfrom

becomingfull.Incaseofsimultaneousrequests,theaccompanyingdiagramshowstheprioritythat

isapplied.Alloftheinterruptrequestflagswhensetwillwake-upthedevicesifitisinSLEEPor

IDLEMode,howevertopreventawake-upfromoccurringthecorrespondingflagshouldbeset

beforethedevicesareinSLEEPorIDLEMode.

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