HT45F56 datasheet(21/90 Pages) HOLTEK

21 / 90 page

Rev. 1.11

April 11, 2017

Rev. 1.11

April 11, 2017

HT45F56

Shock Detector Flash MCU

HT45F56

Shock Detector Flash MCU

Bank Pointer – BP

TheDataMemoryisdividedintotwobanks,Bank0andBank1.SelectingtherequiredData

MemoryareaisachievedusingtheBankPointer,BP.TheBankPointerbit0isusedtoselectData

MemoryBank0orBank1.

TheDataMemoryinitialisedtoBank0afteraresetexceptforaWDTtome-outresetinthePower

DownModeinwhichcasetheDataMemorybankremainsunaffected.Itshouldbenotedthatthe

SpecialFunctionDataMemoryisnotaffectedbythebankselection,whichmeansthattheSpecial

FunctionRegisterscanbeaccessedirrespectiveofthevalueoftheBankPointer.Accessingdata

fromBank1mustbeimplementedusingtheIndirectAddressing.

BP Register

Bit

Name

—

DMBP0

R/W

—

R/W

POR

—

Bit7~1

Unimplemented,readas“0”

Bit0

DMBP0:DataMemoryBankPointbit0

0:Bank0

1:Bank1

Accumulator – ACC

TheAccumulatoriscentraltotheoperationofanymicrocontrollerandiscloselyrelatedwith

operationscarriedoutbytheALU.TheAccumulatoristheplacewhereallintermediateresults

fromtheALUarestored.WithouttheAccumulatoritwouldbenecessarytowritetheresultof

eachcalculationorlogicaloperationsuchasaddition,subtraction,shift,etc.,totheDataMemory

resultinginhigherprogrammingandtimingoverheads.Datatransferoperationsusuallyinvolve

thetemporarystoragefunctionoftheAccumulator;forexample,whentransferringdatabetween

oneuser-definedregisterandanother,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, TBLH

Thesethreespecialfunctionregistersareusedtocontroloperationofthelook-uptablewhichis

storedintheProgramMemory.TBLPisthetablepointerandindicatesthelocationwherethetable

dataislocated.Theirvaluemustbesetupbeforeanytablereadcommandsareexecuted.Theirvalue

canbechanged,forexampleusingthe“INC”or“DEC”instructions,allowingforeasytabledata

pointingandreading.TBLHisthelocationwherethehighorderbyteofthetabledataisstored

afteratablereaddatainstructionhasbeenexecuted.Notethatthelowerordertabledatabyteis

transferredtoauserdefinedlocation.

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