HT45F4M datasheet(84/138 Pages) HOLTEK

84 / 138 page

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HT45F4M

Lithium Battery Backup Power ASSP MCU

HT45F4M

Lithium Battery Backup Power ASSP MCU

Capture Input Mode

ToselectthismodebitsT1M1andT1M0intheTM1C1registershouldbesetto01respectively.

Thismodeenablesexternalsignalstocaptureandstorethepresentvalueoftheinternalcounter

andcanthereforebeusedforapplicationssuchaspulsewidthmeasurements.Theexternalsignalis

suppliedontheTP1orTCK1pin,selectedbytheT1CAPTSbitintheTM1C0register.Theinput

pinactiveedgecanbeeitherarisingedge,afallingedgeorbothrisingandfallingedges;theactive

edgetransitiontypeisselectedusingtheT1IO1andT1IO0bitsintheTM1C1register.Thecounter

isstartedwhentheT1ONbitchangesfromlowtohighwhichisinitiatedusingtheapplication

program.

WhentherequirededgetransitionappearsontheTP1orTCK1pinthepresentvalueinthecounter

willbelatchedintotheCCRAregistersandaTMinterruptgenerated.Irrespectiveofwhatevents

occurontheTP1orTCK1pinthecounterwillcontinuetofreerununtiltheT1ONbitchangesfrom

hightolow.WhenaCCRPcomparematchoccursthecounterwillresetbacktozero;inthisway

theCCRPvaluecanbeusedtocontrolthemaximumcountervalue.WhenaCCRPcomparematch

occursfromComparatorP,aTMinterruptwillalsobegenerated.Countingthenumberofoverflow

interruptsignalsfromtheCCRPcanbeausefulmethodinmeasuringlongpulsewidths.TheT1IO1

andT1IO0bitscanselecttheactivetriggeredgeontheTP1orTCK1pintobearisingedge,falling

edgeorbothedgetypes.IftheT1IO1andT1IO0bitsarebothsethigh,thennocaptureoperation

willtakeplaceirrespectiveofwhathappensontheTP1orTCK1pin,howeveritmustbenotedthat

thecounterwillcontinuetorun.

AstheTP1orTCK1pinispinsharedwithotherfunctions,caremustbetakeniftheTM1isinthe

InputCaptureMode.Thisisbecauseifthepinissetupasanoutput,thenanytransitionsonthispin

maycauseaninputcaptureoperationtobeexecuted.TheT1CCLR,T1OCandT1POLbitsarenot

usedinthisMode.

HT45F4M Datasheet(PDF) 84 Page - Holtek Semiconductor Inc