ETIC 2230 Guide de l'utilisateur télécharger pdf (Page 43)

Rev. 1.10 42 November 14, 2014 Rev. 1.10 43 November 14, 2014

HT66FW2230

Wireless Charger A/D Flash 8-Bit MCU

Bit0 WRF:resetcausedbyWE[4:0]setting

0:Notoccur

1:Occurred

Thisbitissetto1bytheWDTControlregistersoftwareresetandclearedbythe

applicationprogram.Notethatthisbitcanonlybeclearedto0bytheapplication

program.

Watchdog Timer Operation

TheWatchdogTimeroperatesbyprovidingadeviceresetwhenitstimeroverows.Thismeans

thatintheapplicationprogramandduringnormaloperationtheuserhastostrategicallyclearthe

WatchdogTimerbeforeitoverowstopreventtheWatchdogTimerfromexecutingareset.Thisis

doneusingtheclearwatchdoginstruction.Iftheprogrammalfunctionsforwhateverreason,jumps

toanunknownlocation,orentersanendlessloop,thisclearinstructionwillnotbeexecutedinthe

correctmanner,inwhichcasetheWatchdogTimerwilloverowandresetthedevice.Withregardto

theWatchdogTimerenablefunction,therearevebits,WE4~WE0,intheWDTCregistertooffer

theenablecontrolandresetcontroloftheWatchdogTimer.TheWDTfunctionwillbeenabledif

theWE4~WE0bitsareequalto10101or01010B.IftheWE4~WE0bitsaresettoanyothervalues,

otherthan01010Band10101B,itwillresetthedeviceafter2~3LIRCclockcycles.Afterpoweron

thesebitswillhaveavalueof01010B.

WE4 ~ WE0 Bits WDT Function

01010B or 10101B Enable

Any other value Reset MCU

Watchdog Timer Enable/Disable Control

Undernormalprogramoperation,aWatchdogTimertime-outwillinitialiseadeviceresetandset

thestatusbitTO.However,ifthesystemisintheSLEEPorIDLEMode,whenaWatchdogTimer

time-outoccurs,theTObitinthestatusregisterwillbesetandonlytheProgramCounterandStack

Pointerwillbereset.ThreemethodscanbeadoptedtoclearthecontentsoftheWatchdogTimer.

TherstisaWDTsoftwarereset,whichmeansacertainvalueexcept01010Band10101Bwritten

intotheWE4~WE0eld.ThesecondisusingtheWatchdogTimersoftwareclearinstruction.The

thirdisviaaHALTinstruction.

ThereisonlyonemethodofusingsoftwareinstructiontocleartheWatchdogTimer.Thatistouse

thesingle“CLRWDT”instructiontocleartheWDTcontents.

Themaximumtimeoutperiodiswhenthe2

divisionratioisselected.Asanexample,witha32

KHzLIRCoscillatorasitssourceclock,thiswillgiveamaximumwatchdogperiodofaround8

secondforthe2

divisionratio,andaminimumtimeoutof7.8msforthe2

divisionration.

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ETIC 2230 Guide de l'utilisateur Page 43