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Rev. 2.50 216 June 22, 2017 Rev. 2.50 217 June 22, 2017

HT66F20/HT66F30/HT66F40/HT66F50/HT66F60

HT66FU30/HT66FU40/HT66FU50/HT66FU60

A/D Flash MCU with EEPROM

HT66F20/HT66F30/HT66F40/HT66F50/HT66F60

HT66FU30/HT66FU40/HT66FU50/HT66FU60

A/D Flash MCU with EEPROM

Interrupt Operation

Whentheconditionsforaninterrupteventoccur,suchasaTMComparatorP,ComparatorAor

ComparatorBmatchorA/Dconversioncompletionetc,therelevantinterruptrequestagwillbe

set.Whethertherequestagactuallygeneratesaprogramjumptotherelevantinterruptvectoris

determinedbytheconditionoftheinterruptenablebit.Iftheenablebitissethighthentheprogram

willjumptoitsrelevantvector;iftheenablebitiszerothenalthoughtheinterruptrequestagis

setanactualinterruptwillnotbegeneratedandtheprogramwillnotjumptotherelevantinterrupt

vector.Theglobalinterruptenablebit,ifclearedtozero,willdisableallinterrupts.

Whenaninterruptisgenerated,theProgramCounter,whichstorestheaddressofthenextinstruction

tobeexecuted,willbetransferredontothestack.TheProgramCounterwillthenbeloadedwitha

newaddresswhichwillbethevalueofthecorrespondinginterruptvector.Themicrocontrollerwill

thenfetchitsnextinstructionfromthisinterruptvector.Theinstructionatthisvectorwillusually

beaJMPwhichwilljumptoanothersectionofprogramwhichisknownastheinterruptservice

routine.Hereislocatedthecodetocontroltheappropriateinterrupt.Theinterruptserviceroutine

mustbeterminatedwithaRETI,whichretrievestheoriginalProgramCounteraddressfromthe

stackandallowsthemicrocontrollertocontinuewithnormalexecutionatthepointwherethe

interruptoccurred.

Thevariousinterruptenablebits,togetherwiththeirassociatedrequestflags,areshowninthe

accompanyingdiagramswiththeirorderofpriority.Someinterruptsourceshavetheirown

individualvectorwhileotherssharethesamemulti-functioninterruptvector.Onceaninterrupt

subroutineisserviced,alltheotherinterruptswillbeblocked,astheglobalinterruptenablebit,

EMIbitwillbeclearedautomatically.Thiswillpreventanyfurtherinterruptnestingfromoccurring.

However,ifotherinterruptrequestsoccurduringthisinterval,althoughtheinterruptwillnotbe

immediatelyserviced,therequestagwillstillberecorded.

Ifaninterruptrequiresimmediateservicingwhiletheprogramisalreadyinanotherinterruptservice

routine,theEMIbitshouldbesetafterenteringtheroutine,toallowinterruptnesting.Ifthestack

isfull,theinterruptrequestwillnotbeacknowledged,eveniftherelatedinterruptisenabled,until

theStackPointerisdecremented.Ifimmediateserviceisdesired,thestackmustbepreventedfrom

becomingfull.Incaseofsimultaneousrequests,theaccompanyingdiagramshowstheprioritythat

isapplied.Alloftheinterruptrequestagswhensetwillwake-upthedeviceifitisinSLEEPor

IDLEMode,howevertopreventawake-upfromoccurringthecorrespondingagshouldbeset

beforethedeviceisinSLEEPorIDLEMode.

Holtek HT66F30 User Manual

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