HT69F360 datasheet(76/235 Pages) HOLTEK

76 / 235 page

Rev. 1.30

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HT69F340/HT69F350/HT69F360

TinyPowerTM I/O Flash MCU with LCD & EEPROM

HT69F340/HT69F350/HT69F360

TinyPowerTM I/O Flash MCU with LCD & EEPROM

ThereisonlyonemethodofusingsoftwareinstructiontocleartheWatchdogTimer.Thatistouse

thesingle“CLRWDT”instructiontocleartheWDT.

Themaximumtime-outperiodiswhenthe218divisionratioisselected.Asanexample,witha

32kHzLIRCoscillatorasitssourceclock,thiswillgiveamaximumwatchdogperiodofaround8

secondsforthe218divisionratio,andaminimumtimeoutof7.8msforthe28divisionration.

ʺCLR WDTʺ instruction

8-stage Divider

WDT Prescaler

WE4~WE0 bits

WDTC Register

Reset MCU

LXT

fSUB

fS/28

8-to-1 MUX

CLR

WS2~WS0

(fS/28 ~ fS/218)

WDT Time-out

(28/fS ~ 218/fS)

LIRC

FSS bit

ʺHALTʺ instruction

RES pin reset

Watchdog Timer

Reset and Initialisation

Aresetfunctionisafundamentalpartofanymicrocontrollerensuringthatthedevicecanbeset

tosomepredeterminedconditionirrespectiveofoutsideparameters.Themostimportantreset

conditionisafterpowerisfirstappliedtothemicrocontroller.Inthiscase,internalcircuitrywill

ensurethatthemicrocontroller,afterashortdelay,willbeinawelldefinedstateandreadyto

executethefirstprograminstruction.Afterthispower-onreset,certainimportantinternalregisters

willbesettodefinedstatesbeforetheprogramcommences.OneoftheseregistersistheProgram

Counter,whichwillberesettozeroforcingthemicrocontrollertobeginprogramexecutionfromthe

lowestProgramMemoryaddress.

Inadditiontothepower-onreset,situationsmayarisewhereitisnecessarytoforcefullyapplya

resetconditionwhenthemicrocontrollerisrunning.Oneexampleofthisiswhereafterpowerhas

beenappliedandthemicrocontrollerisalreadyrunning,theRESlineisforcefullypulledlow.In

suchacase,knownasanormaloperationreset,someoftheregistersremainunchangedallowing

themicrocontrollertoproceedwithnormaloperationaftertheresetlineisallowedtoreturnhigh.

AnothertypeofresetiswhentheWatchdogTimeroverflowsandresetsthemicrocontroller.All

typesofresetoperationsresultindifferentregisterconditionsbeingsetup.Anotherresetexistsin

theformofaLowVoltageReset,LVR,whereafullreset,similartotheRESresetisimplementedin

situationswherethepowersupplyvoltagefallsbelowacertainthreshold.

Reset Functions

Thereareseveralwaysinwhichamicrocontrollerresetcanoccur,througheventsoccurringboth

internallyandexternally:

Power-on Reset

Themostfundamentalandunavoidableresetistheonethatoccursafterpowerisfirstappliedto

themicrocontroller.AswellasensuringthattheProgramMemorybeginsexecutionfromthefirst

memoryaddress,apower-onresetalsoensuresthatcertainotherregistersarepresettoknown

conditions.AlltheI/Oportandportcontrolregisterswillpowerupinahighconditionensuringthat

allpinswillbefirstsettoinputs.

HT69F360 数据表(PDF) 76 Page - Holtek Semiconductor Inc

HT69F360 数据表(HTML) 76 Page - Holtek Semiconductor Inc

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