HT45F3W datasheet(102/167 Pages) HOLTEK

102 / 167 page

Rev. 1.50

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Rev. 1.50

103

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HT45F3W

R-Type Blood Pressure Meter Flash MCU

HT45F3W

R-Type Blood Pressure Meter Flash MCU

Capture Input Mode

ToselectthismodebitsT2M1andT2M0intheTM2C1registershouldbesetto01respectively.

Thismodeenablesexternalsignalstocaptureandstorethepresentvalueoftheinternalcounter

andcanthereforebeusedforapplicationssuchaspulsewidthmeasurements.Theexternalsignalis

suppliedontheTP2_0orTP2_1pin,whoseactiveedgecanbeeitherarisingedge,afallingedgeor

bothrisingandfallingedges;theactiveedgetransitiontypeisselectedusingtheT2IO1andT2IO0

bitsintheTM2C1register.ThecounterisstartedwhentheT2ONbitchangesfromlowtohigh

whichisinitiatedusingtheapplicationprogram.

WhentherequirededgetransitionappearsontheTP2_0orTP2_1pinthepresentvalueinthe

counterwillbelatchedintotheCCRAregistersandaTMinterruptgenerated.Irrespectiveofwhat

eventsoccurontheTP2_0orTP2_1pinthecounterwillcontinuetofreerununtiltheT2ONbit

changesfromhightolow.WhenaCCRPcomparematchoccursthecounterwillresetbacktozero;

inthiswaytheCCRPvaluecanbeusedtocontrolthemaximumcountervalue.WhenaCCRP

comparematchoccursfromComparatorP,aTMinterruptwillalsobegenerated.Countingthe

numberofoverflowinterruptsignalsfromtheCCRPcanbeausefulmethodinmeasuringlong

pulsewidths.TheT2IO1andT2IO0bitscanselecttheactivetriggeredgeontheTP2_0orTP2_1

pintobearisingedge,fallingedgeorbothedgetypes.IftheT2IO1andT2IO0bitsarebothset

high,thennocaptureoperationwilltakeplaceirrespectiveofwhathappensontheTP2_0orTP2_1

pin,howeveritmustbenotedthatthecounterwillcontinuetorun.

AstheTP2_0orTP2_1pinispinsharedwithotherfunctions,caremustbetakeniftheTMisinthe

InputCaptureMode.Thisisbecauseifthepinissetupasanoutput,thenanytransitionsonthispin

maycauseaninputcaptureoperationtobeexecuted.TheT2CCLRandT2DPXbitsarenotusedin

thisMode.

HT45F3W Datasheet(PDF) 102 Page - Holtek Semiconductor Inc