HT48R002 datasheet(39/71 Pages) HOLTEK

39 / 71 page

Rev. 1.11

April 11, 2017

Rev. 1.11

April 11, 2017

HT48R002/HT48R003

Cost-Effective I/O 8-Bit OTP MCU

HT48R002/HT48R003

Cost-Effective I/O 8-Bit OTP MCU

Timer Register – TMR0

ThetimerregisterisspecialfunctionregisterlocatedintheSpecialPurposeDataMemoryandisthe

placewheretheactualtimervalueisstored.TheregisterisknownasTMR0.Thevalueinthetimer

registerincreasesbyoneeachtimeaninternalclockpulseisreceivedoranexternaltransitionoccurs

ontheexternaltimerpin.Thetimerwillcountfromtheinitialvalueloadedbythepreloadregisterto

thefullcountofFFHatwhichpointthetimeroverflowsandaninternalinterruptsignalisgenerated.

Thetimervaluewillthenresetwiththeinitialpreloadregistervalueandcontinuecounting.

NotethattoachieveamaximumfullrangecountofFFH,thepreloadregistermustfirstbecleared.

Itshouldbenotedthatafterpower-on,thepreloadregisterwillbeinanunknowncondition.Note

thatiftheTimer/EventCounterisinanOFFconditionanddataiswrittentoitspreloadregister,

thisdatawillbeimmediatelywrittenintotheactualcounter.However,ifthecounterisenabledand

counting,anynewdatawrittenintothepreloaddataregisterduringthisperiodwillremaininthe

preloadregisterandwillonlybewrittenintotheactualcounterthenexttimeanoverflowoccurs.

Timer Control Register – TMR0C

TheflexiblefeaturesoftheHoltekmicrocontrollerTimer/EventCounterenableittooperateinthree

differentmodes,theoptionsofwhicharedeterminedbythecontentsoftheirrespectivecontrol

TheTimerControlRegisterisknownasTMR0C.ItistheTimerControlRegistertogetherwith

itscorrespondingtimerregisterthatcontrolsthefulloperationoftheTimer/EventCounter.Before

thetimercanbeused,itisessentialthattheTimerControlRegisterisfullyprogrammedwiththe

rightdatatoensureitscorrectoperation,aprocessthatisnormallycarriedoutduringprogram

initialization.

Tochoosewhichofthethreemodesthetimeristooperatein,eitherinthetimermode,theevent

countingmodeorthepulsewidthcapturemode,bits7and6oftheTimerControlRegister,which

areknownasthebitpairT0M1/T0M0,mustbesettotherequiredlogiclevels.Thetimer-onbit,

whichisbit4oftheTimerControlRegisterandknownasT0ON,providesthebasicon/offcontrol

oftherespectivetimer.Settingthebittohighallowsthecountertorun.Clearingthebitstopsthe

counter.Bits0~2oftheTimerControlRegisterdeterminethedivisionratiooftheinputclock

prescaler.Theprescalerbitsettingshavenoeffectifanexternalclocksourceisused.Ifthetimeris

intheeventcountorpulsewidthcapturemode,theactivetransitionedgeleveltypeisselectedby

thelogiclevelofbit3oftheTimerControlRegisterwhichisknownasT0EG.

HT48R002 датащи(PDF) 39 Page - Holtek Semiconductor Inc