HT45F56 datasheet(39/90 Pages) HOLTEK

39 / 90 page

Rev. 1.11

April 11, 2017

Rev. 1.11

April 11, 2017

HT45F56

Shock Detector Flash MCU

HT45F56

Shock Detector Flash MCU

SMOD1 Register

Bit

Name

FSYSON

—

RSTF

LVRF

—

WRF

R/W

—

R/W

—

R/W

POR

—

“x”: unknown

Bit7

FSYSON:fSYScontrolinIDLEmode

Describedelsewhere.

Bit6~4

Unimplemented,readas“0”

Bit3

RSTF:Resetcontrolregistersoftwareresetflag

Describedelsewhere.

Bit2

LVRF:LVRfunctionresetflag

Describedelsewhere.

Bit1

Unimplemented,readas“0”

Bit0

WRF:WDTcontrolregistersoftwareresetflag

0:Notoccurred

1:Occurred

Thisbitissetto1bytheWDTcontrolregistersoftwareresetandclearedbythe

applicationprogram.Notethatthisbitcanonlybeclearedto0bytheapplicationprogram.

Watchdog Timer Operation

TheWatchdogTimeroperatesbyprovidingadeviceresetwhenitstimeroverflows.Thismeans

thatintheapplicationprogramandduringnormaloperationtheuserhastostrategicallyclearthe

WatchdogTimerbeforeitoverflowstopreventtheWatchdogTimerfromexecutingareset.Thisis

doneusingtheclearwatchdoginstruction.Iftheprogrammalfunctionsforwhateverreason,jumps

toanunknownlocation,orentersanendlessloop,theclearinstructionwillnotbeexecutedinthe

correctmanner,inwhichcasetheWatchdogTimerwilloverflowandresetthedevice.Withregardto

theWatchdogTimerenable/disablefunction,therearefivebits,WE4~WE0,intheWDTCregister

tooffertheenable/disablecontrolandresetcontroloftheWatchdogTimer.TheWDTfunctionwill

bedisabledwhentheWE4~WE0bitsaresettoavalueof10101BwhiletheWDTfunctionwill

beenablediftheWE4~WE0bitsareequalto01010B.IftheWE4~WE0bitsaresettoanyother

values,otherthan01010Band10101B,itwillresetthedeviceafter2~3fLIRC

clockcycles.After

poweronthesebitswillhaveavalueof01010B.

WE4 ~ WE0 Bits

WDT Function

10101B

Disable

01010B

Enable

Any other value

Reset MCU

Watchdog Timer Enable/Disable Control

Undernormalprogramoperation,aWatchdogTimertime-outwillinitialiseadeviceresetandset

thestatusbitTO.However,ifthesystemisintheSLEEPorIDLEMode,whenaWatchdogTimer

time-outoccurs,theTObitinthestatusregisterwillbesetandonlytheProgramCounterandStack

Pointerwillbereset.FourmethodscanbeadoptedtoclearthecontentsoftheWatchdogTimer.

ThefirstisaWDTreset,whichmeansacertainvalueexcept01010Band10101Bwrittenintothe

WE4~WE0field,thesecondisusingtheWatchdogTimersoftwareclearinstruction,thethirdis

usingaHALTinstructionandthefourthisanexternalhardwarereset.

ThereisonlyonemethodofusingsoftwareinstructiontocleartheWatchdogTimer.Thatistouse

thesingle“CLRWDT”instructiontocleartheWDTcontents.

HT45F56 Datasheet(PDF) 39 Page - Holtek Semiconductor Inc

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