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поискавой системы для электроныых деталей |
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поискавой системы для электроныых деталей |
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HT45F5R датащи(PDF) 49 Page - Holtek Semiconductor Inc |
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HT45F5R датащи(HTML) 49 Page - Holtek Semiconductor Inc |
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49 / 138 page  Rev. 1.10 48 De�e��e� 1�� �01� Rev. 1.10 49 De�e��e� 1�� �01� HT45F5R Charger ASSP Flash MCU HT45F5R Charger ASSP Flash MCU Reset and Initialisation Aresetfunctionisafundamentalpartofanymicrocontrollerensuringthatthedevicecanbeset tosomepredeterminedconditionirrespectiveofoutsideparameters.Themostimportantreset conditionisafterpowerisfirstappliedtothemicrocontroller.Inthiscase,internalcircuitrywill ensurethatthemicrocontroller,afterashortdelay,willbeinawelldefinedstateandreadyto executethefirstprograminstruction.Afterthispower-onreset,certainimportantinternalregisters willbesettodefinedstatesbeforetheprogramcommences.OneoftheseregistersistheProgram Counter,whichwillberesettozeroforcingthemicrocontrollertobeginprogramexecutionfromthe lowestProgramMemoryaddress. AnothertypeofresetiswhentheWatchdogTimeroverflowsandresetsthemicrocontroller.All typesofresetoperationsresultindifferentregisterconditionsbeingsetup.Anotherresetexistsinthe formofaLowVoltageReset,LVR,whereafullresetisimplementedinsituationswherethepower supplyvoltagefallsbelowacertainthreshold. Reset Functions Thereareseveralwaysinwhichamicrocontrollerresetcanoccur,eachofwhichwillbedescribed asfollows. Power-on Reset Themostfundamentalandunavoidableresetistheonethatoccursafterpowerisfirstappliedto themicrocontroller.AswellasensuringthattheProgramMemorybeginsexecutionfromthefirst memoryaddress,apower-onresetalsoensuresthatcertainotherregistersarepresettoknown conditions.AlltheI/Oportandportcontrolregisterswillpowerupinahighconditionensuringthat allpinswillbefirstsettoinputs. VDD Powe�-on Reset SST Ti�e-out tRSTD Note:tRSTDispower-ondelaywithtypicaltime=50ms Power-On Reset Timing Chart Low Voltage Reset — LVR Themicrocontrollercontainsalowvoltageresetcircuitinordertomonitorthesupplyvoltageofthe deviceandprovideanMCUresetshouldthevaluefallbelowacertainpredefinedlevel.TheLVR functionisalwaysenabledduringthenormalandslowmodeswithaspecificLVRvoltageVLVR.If thesupplyvoltageofthedevicedropstowithinarangeof0.9V~VLVRsuchasmightoccurwhen changingthebattery,theLVRwillautomaticallyresetthedeviceinternallyandtheLVRFbitinthe RSTFCregisterwillalsobesetto1.ForavalidLVRsignal,alowvoltage,i.e.,avoltageintherange between0.9V~VLVRmustexistforgreaterthanthevaluetLVRspecifiedintheLVD&LVRElectrical Characteristics.Ifthelowvoltagestatedoesnotexceedthisvalue,theLVRwillignorethelow supplyvoltageandwillnotperformaresetfunction.TheactualVLVRis2.1V,theLVRwillresetthe deviceafter2~3LIRCclockcycles.NotethattheLVRfunctionwillbeautomaticallydisabledwhen thedeviceentersthepowerdownmode. LVR Inte�nal Reset tRSTD + tSST Note:tRSTDispower-ondelaywithtypicaltime=50ms Low Voltage Reset Timing Chart |
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