HT82B42R datasheet(67/86 Pages) HOLTEK

67 / 86 page

Rev. 1.00

October 27, 2011

Rev. 1.00

October 27, 2011

HT82B42R/HT82B42RE

I/O MCU with USB Interface

Instruction Set

Introduction

Centraltothesuccessfuloperationofanymicrocontrollerisitsinstructionset,whichisasetof

programinstructioncodesthatdirectsthemicrocontrollertoperformcertainoperations.Inthecase

ofHoltekmicrocontrollers,acomprehensiveandflexiblesetofover60instructionsisprovidedto

enableprogrammerstoimplementtheirapplicationwiththeminimumofprogrammingoverheads.

Foreasierunderstandingofthevariousinstructioncodes,theyhavebeensubdividedintoseveral

functionalgroupings.

Instruction Timing

Mostinstructionsareimplementedwithinoneinstructioncycle.Theexceptionstothisarebranch,

call,ortablereadinstructionswheretwoinstructioncyclesarerequired.Oneinstructioncycleis

equalto4systemclockcycles,thereforeinthecaseofan8MHzsystemoscillator,mostinstructions

wouldbeimplementedwithin0.5µsandbranchorcallinstructionswouldbeimplementedwithin

1µs.Althoughinstructionswhichrequireonemorecycletoimplementaregenerallylimitedto

theJMP,CALL,RET,RETIandtablereadinstructions,itisimportanttorealizethatanyother

instructionswhichinvolvemanipulationoftheProgramCounterLowregisterorPCLwillalsotake

onemorecycletoimplement.AsinstructionswhichchangethecontentsofthePCLwillimplya

directjumptothatnewaddress,onemorecyclewillberequired.Examplesofsuchinstructions

wouldbe″CLRPCL″or″MOVPCL,A″.Forthecaseofskipinstructions,itmustbenotedthatif

theresultofthecomparisoninvolvesaskipoperationthenthiswillalsotakeonemorecycle,ifno

skipisinvolvedthenonlyonecycleisrequired.

Moving and Transferring Data

Thetransferofdatawithinthemicrocontrollerprogramisoneofthemostfrequentlyused

operations.MakinguseofthreekindsofMOVinstructions,datacanbetransferredfromregistersto

theAccumulatorandvice-versaaswellasbeingabletomovespecificimmediatedatadirectlyinto

theAccumulator.Oneofthemostimportantdatatransferapplicationsistoreceivedatafromthe

inputportsandtransferdatatotheoutputports.

Arithmetic Operations

Theabilitytoperformcertainarithmeticoperationsanddatamanipulationisanecessaryfeatureof

mostmicrocontrollerapplications.WithintheHoltekmicrocontrollerinstructionsetarearangeof

addandsubtractinstructionmnemonicstoenablethenecessaryarithmetictobecarriedout.Care

mustbetakentoensurecorrecthandlingofcarryandborrowdatawhenresultsexceed255for

additionandlessthan0forsubtraction.TheincrementanddecrementinstructionsINC,INCA,DEC

andDECAprovideasimplemeansofincreasingordecreasingbyavalueofoneofthevaluesinthe

destinationspecified.

HT82B42R Datasheet(PDF) 67 Page - Holtek Semiconductor Inc