HT83B60 datasheet(29/84 Pages) HOLTEK

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HT83B60

Voice Mask MCU

HT83B60

Voice Mask MCU

Timers

Theprovisionoftimersformanimportantpartofanymicrocontroller,givingthedesignerameans

ofcarryingouttimerelatedfunctions.Thesedevicescontaintwocountuptimersof8-bitcapacity.

Theprovisionofaninternalprescalertotheclockcircuitryofthetimergivesaddedrangetothe

timer.

TherearetwotypesofregisterrelatedtoeachTimer.Thefirstistheregisterthatcontainstheactual

valueofthetimerandintowhichaninitialvaluecanbepreloaded.Readingfromthisregister

retrievesthecontentsoftheTimer.Alldevicescanhavethetimerclockconfiguredtocomefromthe

internalclocksource.

Ti me r M ode C ont ro l

T0 ON

T1 ON

Pr el oad Re gi st er

Ti me r

Da ta B us

Re l oad

Ov er fl ow

to I nt er ru pt

T1 PS C2 ~T 1P SC 0

T0 PS C2 ~T 0P SC 0

8- Bi t C ount er

f SY S

Pr e sca le r

(1 /2 ~1 /2 56)

T1 TM 1

T0 TM 1

T1 TM 0

T0 TM 0

8-bit Timer Structure

Configuring the Timer Input Clock Source

Theclocksourceforthe8-bittimersisthesystemclockdividedbyfour.The8-bittimerclock

sourceisalsofirstdividedbya,thedivisionratioofwhichisconditionedbythethreelowerbitsof

theassociatedtimercontrolregister.

Timer Registers - TMR0, TMR1

ThetimerregistersarespecialfunctionregisterslocatedinthespecialpurposeDataMemoryandis

theplacewheretheactualtimervalueisstored.Alldevicescontaintwo8-bittimers,whoseregisters

areknownasTMR0andTMR1.Thevalueinthetimerregistersincreasesbyoneeachtimean

internalclockpulseisreceived.Thetimerwillcountfromtheinitialvalueloadedbythepreload

registertothefullcountofFFHforthe8-bittimeratwhichpointthetimeroverflowsandaninternal

interruptsignalisgenerated.Thetimervaluewillthenberesetwiththeinitialpreloadregistervalue

andcontinuecounting.

NotethattoachieveamaximumfullrangecountofFFHforthe8-bittimer,thepreloadregisters

mustfirstbeclearedtoallzeros.Itshouldbenotedthatafterpower-on,thepreloadregisterswillbe

inanunknowncondition.NotethatiftheTimerCountersareinanOFFconditionanddataiswritten

totheirpreloadregisters,thisdatawillbeimmediatelywrittenintotheactualcounter.However,if

thecounterisenabledandcounting,anynewdatawrittenintothepreloaddataregisterduringthis

periodwillremaininthepreloadregisterandwillonlybewrittenintotheactualcounterthenext

timeanoverflowoccurs.Notealsothatwhenthetimerregistersareread,thetimerclockwillbe

blockedtoavoiderrors,however,asthismayresultincertaintimingerrors,programmersmusttake

thisintoaccount.

HT83B60 Datasheet(PDF) 29 Page - Holtek Semiconductor Inc

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