HT68F005 datasheet(23/93 Pages) HOLTEK

23 / 93 page

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HT68F005/HT68F006

Enhanced I/O Flash Type MCU

HT68F005/HT68F006

Enhanced I/O Flash Type MCU

Accumulator – ACC

TheAccumulatoriscentraltotheoperationofanymicrocontrollerandiscloselyrelatedwith

operationscarriedoutbytheALU.TheAccumulatoristheplacewhereallintermediateresults

fromtheALUarestored.WithouttheAccumulatoritwouldbenecessarytowritetheresultof

eachcalculationorlogicaloperationsuchasaddition,subtraction,shift,etc.,totheDataMemory

resultinginhigherprogrammingandtimingoverheads.Datatransferoperationsusuallyinvolve

thetemporarystoragefunctionoftheAccumulator;forexample,whentransferringdatabetween

oneuserdefinedregisterandanother,itisnecessarytodothisbypassingthedatathroughthe

Accumulatorasnodirecttransferbetweentworegistersispermitted.

Program Counter Low Register – PCL

Toprovideadditionalprogramcontrolfunctions,thelowbyteoftheProgramCounterismade

accessibletoprogrammersbylocatingitwithintheSpecialPurposeareaoftheDataMemory.By

manipulatingthisregister,directjumpstootherprogramlocationsareeasilyimplemented.Loading

avaluedirectlyintothisPCLregisterwillcauseajumptothespecifiedProgramMemorylocation,

however,astheregisterisonly8-bitwide,onlyjumpswithinthecurrentProgramMemorypageare

permitted.Whensuchoperationsareused,notethatadummycyclewillbeinserted.

Look-up Table Registers – TBLP, TBHP, TBLH

Thesethreespecialfunctionregistersareusedtocontroloperationofthelook-uptablewhichis

storedintheProgramMemory.TBLPandTBHParethetablepointerandindicatesthelocation

wherethetabledataislocated.Theirvaluemustbesetupbeforeanytablereadcommandsare

executed.Theirvaluecanbechanged,forexampleusingthe“INC”or“DEC”instructions,allowing

foreasytabledatapointingandreading.TBLHisthelocationwherethehighorderbyteofthetable

dataisstoredafteratablereaddatainstructionhasbeenexecuted.Notethatthelowerordertable

databyteistransferredtoauserdefinedlocation.

Status Register – STATUS

This8-bitregistercontainsthezeroflag(Z),carryflag(C),auxiliarycarryflag(AC),overflowflag

(OV),powerdownflag(PDF),andwatchdogtime-outflag(TO).Thesearithmetic/logicaloperation

andsystemmanagementflagsareusedtorecordthestatusandoperationofthemicrocontroller.

WiththeexceptionoftheTOandPDFflags,bitsinthestatusregistercanbealteredbyinstructions

likemostotherregisters.AnydatawrittenintothestatusregisterwillnotchangetheTOorPDFflag.

Inaddition,operationsrelatedtothestatusregistermaygivedifferentresultsduetothedifferent

instructionoperations.TheTOflagcanbeaffectedonlybyasystempower-up,aWDTtime-outor

byexecutingthe"CLRWDT"or"HALT"instruction.ThePDFflagisaffectedonlybyexecuting

the"HALT"or"CLRWDT"instructionorduringasystempower-up.

HT68F005 Datasheet(PDF) 23 Page - Holtek Semiconductor Inc

HT68F005 Datasheet(HTML) 23 Page - Holtek Semiconductor Inc

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