ETIC 2230 Guia do Utilizador descarregar pdf (Página 25)

Rev. 1.10 24 November 14, 2014 Rev. 1.10 25 November 14, 2014

HT66FW2230

Wireless Charger A/D Flash 8-Bit MCU

Accumulator – ACC

TheAccumulatoriscentraltotheoperationofanymicrocontroller andiscloselyrelatedwith

operationscarriedoutbytheALU.TheAccumulatoristheplacewhereallintermediateresults

fromtheALUarestored.WithouttheAccumulatoritwouldbenecessarytowritetheresultof

eachcalculationorlogicaloperationsuchasaddition,subtraction,shift,etc.,totheDataMemory

resultinginhigherprogrammingandtimingoverheads.Datatransferoperationsusuallyinvolve

thetemporarystoragefunctionoftheAccumulator;forexample,whentransferringdatabetween

oneuser-definedregisterandanother,itisnecessarytodothisbypassingthedatathroughthe

Accumulatorasnodirecttransferbetweentworegistersispermitted.

Program Counter Low Register – PCL

Toprovideadditionalprogramcontrolfunctions,thelowbyteoftheProgramCounterismade

accessibletoprogrammersbylocatingitwithintheSpecialPurposeareaoftheDataMemory.By

manipulatingthisregister,directjumpstootherprogramlocationsareeasilyimplemented.Loading

avaluedirectlyintothisPCLregisterwillcauseajumptothespeciedProgramMemorylocation,

however,astheregisterisonly8-bitwide,onlyjumpswithinthecurrentProgramMemorypageare

permitted.Whensuchoperationsareused,notethatadummycyclewillbeinserted.

Look-up Table Registers – TBLP, TBHP, TBLH

Thesethreespecialfunctionregistersareusedtocontroloperationofthelook-uptablewhichis

storedintheProgramMemory.TBLPandTBHParethetablepointersandindicatethelocation

wherethetabledataislocated.Theirvaluemustbesetupbeforeanytablereadcommandsare

executed.Theirvaluecanbechanged,forexampleusingthe“INC”or“DEC”instructions,allowing

foreasytabledatapointingandreading.TBLHisthelocationwherethehighorderbyteofthetable

dataisstoredafteratablereaddatainstructionhasbeenexecuted.Notethatthelowerordertable

databyteistransferredtoauserdenedlocation.

Status Register – STATUS

This8-bitregistercontainstheSC,CZ,zeroflag(Z),carryflag(C),auxiliarycarryflag(AC),

overowag(OV),powerdownag(PDF),andwatchdogtime-outag(TO).Thesearithmetic/

logicaloperationandsystemmanagementagsareusedtorecordthestatusandoperationofthe

microcontroller.

WiththeexceptionoftheTOandPDFags,bitsinthestatusregistercanbealteredbyinstructions

likemostotherregisters.AnydatawrittenintothestatusregisterwillnotchangetheTOorPDFag.

Inaddition,operationsrelatedtothestatusregistermaygivedifferentresultsduetothedifferent

instructionoperations.TheTOagcanbeaffectedonlybyasystempower-up,aWDTtime-outor

byexecutingthe“CLRWDT”or“HALT”instruction.ThePDFagisaffectedonlybyexecuting

the“HALT”or“CLRWDT”instructionorduringasystempower-up.

TheSC,CZ,Z,OV,ACandCagsgenerallyreectthestatusofthelatestoperations.

• Cissetifanoperationresultsinacarryduringanadditionoperationorifaborrowdoesnottake

placeduringasubtractionoperation;otherwiseCiscleared.Cisalsoaffectedbyarotatethrough

carryinstruction.

• ACissetifanoperationresultsinacarryoutofthelownibblesinaddition,ornoborrowfrom

thehighnibbleintothelownibbleinsubtraction;otherwiseACiscleared.

• Zissetiftheresultofanarithmeticorlogicaloperationiszero;otherwiseZiscleared.

• OVissetifanoperationresultsinacarryintothehighest-orderbitbutnotacarryoutofthe

highest-orderbit,orviceversa;otherwiseOViscleared.

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