HT45F56 datasheet(14/90 Pages) HOLTEK

14 / 90 page

Rev. 1.11

April 11, 2017

Rev. 1.11

April 11, 2017

HT45F56

Shock Detector Flash MCU

HT45F56

Shock Detector Flash MCU

Stack

ThisisaspecialpartofthememorywhichisusedtosavethecontentsoftheProgramCounter

only.Thestackhasmultiplelevelsandisneitherpartofthedatanorpartoftheprogramspace,

andisneitherreadablenorwriteable.TheactivatedlevelisindexedbytheStackPointer,andis

neitherreadablenorwriteable.Atasubroutinecallorinterruptacknowledgesignal,thecontentsof

theProgramCounterarepushedontothestack.Attheendofasubroutineoraninterruptroutine,

signaledbyareturninstruction,RETorRETI,theProgramCounterisrestoredtoitspreviousvalue

fromthestack.Afteradevicereset,theStackPointerwillpointtothetopofthestack.

Ifthestackisfullandanenabledinterrupttakesplace,theinterruptrequestflagwillberecordedbut

theacknowledgesignalwillbeinhibited.WhentheStackPointerisdecremented,byRETorRETI,

theinterruptwillbeserviced.Thisfeaturepreventsstackoverflowallowingtheprogrammertouse

thestructuremoreeasily.However,whenthestackisfull,aCALLsubroutineinstructioncanstill

beexecutedwhichwillresultinastackoverflow.Precautionsshouldbetakentoavoidsuchcases

whichmightcauseunpredictableprogrambranching.

Ifthestackisoverflow,thefirstProgramCountersaveinthestackwillbelost.

Stack

Pointer

Stack Level 2

Stack Level 1

Program Memory

Program Counter

Bottom of Stack

Top of Stack

Arithmetic and Logic Unit – ALU

Thearithmetic-logicunitorALUisacriticalareaofthemicrocontrollerthatcarriesoutarithmetic

andlogicoperationsoftheinstructionset.Connectedtothemainmicrocontrollerdatabus,theALU

receivesrelatedinstructioncodesandperformstherequiredarithmeticorlogicaloperationsafter

whichtheresultwillbeplacedinthespecifiedregister.AstheseALUcalculationoroperationsmay

resultincarry,borroworotherstatuschanges,thestatusregisterwillbecorrespondinglyupdatedto

reflectthesechanges.TheALUsupportsthefollowingfunctions:

• Arithmeticoperations:

ADD,ADDM,ADC,ADCM,SUB,SUBM,SBC,SBCM,DAA

• Logicoperations:

AND,OR,XOR,ANDM,ORM,XORM,CPL,CPLA

• Rotation:

RRA,RR,RRCA,RRC,RLA,RL,RLCA,RLC

• IncrementandDecrement:

INCA,INC,DECA,DEC

• Branchdecision:

JMP,SZ,SZA,SNZ,SIZ,SDZ,SIZA,SDZA,CALL,RET,RETI

HT45F56 数据表(PDF) 14 Page - Holtek Semiconductor Inc

HT45F56 数据表(HTML) 14 Page - Holtek Semiconductor Inc

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