HT45F56 datasheet(22/90 Pages) HOLTEK

22 / 90 page

Rev. 1.11

April 11, 2017

Rev. 1.11

April 11, 2017

HT45F56

Shock Detector Flash MCU

HT45F56

Shock Detector Flash MCU

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.

TheZ,OV,ACandCflagsgenerallyreflectthestatusofthelatestoperations.

• Cissetifanoperationresultsinacarryduringanadditionoperationorifaborrowdoesnottake

placeduringasubtractionoperation;otherwiseCiscleared.Cisalsoaffectedbyarotatethrough

carryinstruction.

• ACissetifanoperationresultsinacarryoutofthelownibblesinaddition,ornoborrowfrom

thehighnibbleintothelownibbleinsubtraction;otherwiseACiscleared.

• Zissetiftheresultofanarithmeticorlogicaloperationiszero;otherwiseZiscleared.

• OVissetifanoperationresultsinacarryintothehighest-orderbitbutnotacarryoutofthe

highest-orderbit,orviceversa;otherwiseOViscleared.

• PDFisclearedbyasystempower-uporexecutingthe“CLRWDT”instruction.PDFissetby

executingthe“HALT”instruction.

• TOisclearedbyasystempower-uporexecutingthe“CLRWDT”or“HALT”instruction.TOis

setbyaWDTtime-out.

Inaddition,onenteringaninterruptsequenceorexecutingasubroutinecall,thestatusregisterwill

notbepushedontothestackautomatically.Ifthecontentsofthestatusregistersareimportantandif

thesubroutinecancorruptthestatusregister,precautionsmustbetakentocorrectlysaveit.

HT45F56 数据表(PDF) 22 Page - Holtek Semiconductor Inc