HT45F75 datasheet(59/190 Pages) HOLTEK

59 / 190 page

Rev. 1.10

De�e��e� 1�� 01�

Rev. 1.10

De�e��e� 1�� 01�

HT45F75

Body Fat Scale Flash MCU

HT45F75

Body Fat Scale Flash MCU

Watchdog Timer Operation

TheWatchdogTimeroperatesbyprovidingadeviceresetwhenitstimeroverflows.Thismeans

thatintheapplicationprogramandduringnormaloperationtheuserhastostrategicallyclearthe

WatchdogTimerbeforeitoverflowstopreventtheWatchdogTimerfromexecutingareset.Thisis

doneusingtheclearwatchdoginstructions.Iftheprogrammalfunctionsforwhateverreason,jumps

toanunknownlocation,orentersanendlessloop,theseclearinstructionswillnotbeexecutedinthe

correctmanner,inwhichcasetheWatchdogTimerwilloverflowandresetthedevice.Someofthe

WatchdogTimeroptions,suchasalwaysonselectusingconfigurationoptions.Withregardtothe

WatchdogTimerenable/disablefunction,therearealsofivebits,WE4~WE0,intheWDTCregister

toofferadditionalenable/disableandresetcontroloftheWatchdogTimer.IftheWDTconfiguration

optionisdeterminedthattheWDTfunctionisalwaysenabled,theWE4~WE0bitsstillhave

effectsontheWDTfunction.WhentheWE4~WE0bitsvalueisequalto01010Bor10101B,the

WDTfunctionisenabled.However,iftheWE4~WE0bitsarechangedtoanyothervaluesexcept

01010Band10101B,whichiscausedbytheenvironmentalnoiseorsoftwaresetting,itwillreset

themicrocontrollerafter2~3fSUBclockcycles.IftheWDTconfigurationoptionisdeterminedthat

theWDTfunctioniscontrolledbytheWDTcontrolregister,theWE4~WE0valuescandetermine

whichmodetheWDToperatesin.TheWDTfunctionwillbedisabledwhentheWE4~WE0bitsare

settoavalueof10101B.TheWDTfunctionwillbeenablediftheWE4~WE0bitsvalueisequalto

01010B.IftheWE4~WE0bitsaresettoanyothervaluesbytheenvironmentalnoiseorsoftware

setting,except01010Band10101B,itwillresetthedeviceafter2~3fSUBclockcycles.Afterpower

onthesebitswillhavethevalueof01010B.

WDT Configuration Option

WE4 ~ WE0 Bits

WDT Function

Always Ena�le

01010B o� 10101B

Ena�le

Any othe� values

Reset MCU

Cont�olled �y WDT Cont�ol Registe�

10101B

Disa�le

01010B

Ena�le

Any othe� values

Reset MCU

Watchdog Timer Enable/Disable Control

Undernormalprogramoperation,aWatchdogTimertime-outwillinitialiseadeviceresetandset

thestatusbitTO.However,ifthesystemisintheSLEEPorIDLEMode,whenaWatchdogTimer

time-outoccurs,theTObitinthestatusregisterwillbesetandonlytheProgramCounterandStack

Pointerwillbereset.ThreemethodscanbeadoptedtoclearthecontentsoftheWatchdogTimer.

ThefirstisaWDTreset,whichmeansacertainvalueexcept01010Band10101Bwrittenintothe

WE4~WE0bitfiled,thesecondisusingtheWatchdogTimersoftwareclearinstructionsandthe

thirdisviaaHALTinstruction.

ThereisonlyonemethodofusingsoftwareinstructiontocleartheWatchdogTimer.Thatistouse

thesingle“CLRWDT”instructiontocleartheWDT.

Themaximumtimeoutperiodiswhenthe218divisionratioisselected.Asanexample,witha

32kHzLIRCoscillatorasitssourceclock,thiswillgiveamaximumwatchdogperiodofaround8

secondforthe218divisionratio,andaminimumtimeoutof7.8msforthe28divisionration.

HT45F75 Fiches technique(PDF) 59 Page - Holtek Semiconductor Inc

HT45F75 Fiches technique(HTML) 59 Page - Holtek Semiconductor Inc

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 ...More

Fiches technique Télécharger

Lien URL