HT45F3520 datasheet(45/134 Pages) HOLTEK

45 / 134 page

Rev. 1.10

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Rev. 1.10

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HT45F3520/HT45F3530

Personal Care Flash MCU

HT45F3520/HT45F3530

Personal Care Flash MCU

Wake-up

AfterthesystementerstheSLEEPorIDLEMode,itcanbewokenupfromoneofvarioussources

listedasfollows:

• AnexternalfallingedgeonPortA

• Asysteminterrupt

• AWDToverflow

IfthedevicesarewokenupbyaWDToverflow,aWatchdogTimerresetwillbeinitiated.Although

bothofthesewake-upmethodswillinitiatearesetoperation,theactualsourceofthewake-upcan

bedeterminedbyexaminingtheTOandPDFflags.ThePDFflagisclearedbyasystempower-upor

executingtheclearWatchdogTimerinstructionsandissetwhenexecutingthe"HALT"instruction.

TheTOflagissetifaWDTtime-outoccurs,andcausesawake-upthatonlyresetstheProgram

CounterandStackPointer,theotherflagsremainintheiroriginalstatus.

EachpinonPortAcanbesetupusingthePAWUregistertopermitanegativetransitiononthepin

towake-upthesystem.WhenaPortApinwake-upoccurs,theprogramwillresumeexecutionat

theinstructionfollowingthe"HALT"instruction.Ifthesystemiswokenupbyaninterrupt,then

twopossiblesituationsmayoccur.Thefirstiswheretherelatedinterruptisdisabledortheinterrupt

isenabledbutthestackisfull,inwhichcasetheprogramwillresumeexecutionattheinstruction

followingthe"HALT"instruction.Inthissituation,theinterruptwhichwoke-upthedevicewillnot

beimmediatelyserviced,butwillratherbeservicedlaterwhentherelatedinterruptisfinallyenabled

orwhenastacklevelbecomesfree.Theothersituationiswheretherelatedinterruptisenabledand

thestackisnotfull,inwhichcasetheregularinterruptresponsetakesplace.Ifaninterruptrequest

flagissethighbeforeenteringtheSLEEPorIDLEMode,thewake-upfunctionoftherelated

interruptwillbedisabled.

HT45F3520 Datasheet(PDF) 45 Page - Holtek Semiconductor Inc