HT45F2020 datasheet(57/85 Pages) HOLTEK

57 / 85 page

Rev. 1.00

April 11, 2017

Rev. 1.00

April 11, 2017

HT45F2020/HT45F2022

Sound Effect Generator Flash MCU

HT45F2020/HT45F2022

Sound Effect Generator Flash MCU

Capture Input Mode

ToselectthismodebitsPTM1andPTM0inthePTMC1registershouldbesetto01respectively.

Thismodeenablesexternalsignalstocaptureandstorethepresentvalueoftheinternalcounter

andcanthereforebeusedforapplicationssuchaspulsewidthmeasurements.Theexternalsignalis

suppliedonthePTPIorPTCKpin,selectedbythePTCAPTSbitinthePTMC1register.Theinput

pinactiveedgecanbeeitherarisingedge,afallingedgeorbothrisingandfallingedges;theactive

edgetransitiontypeisselectedusingthePTIO1andPTIO0bitsinthePTMC1register.Thecounter

isstartedwhenthePTONbitchangesfromlowtohighwhichisinitiatedusingtheapplication

program.

WhentherequirededgetransitionappearsonthePTPIorPTCKpinthepresentvalueinthecounter

willbelatchedintotheCCRAregistersandaPTMinterruptgenerated.Irrespectiveofwhatevents

occuronthePTPIorPTCKpinthecounterwillcontinuetofreerununtilthePTONbitchanges

fromhightolow.WhenaCCRPcomparematchoccursthecounterwillresetbacktozero;inthis

waytheCCRPvaluecanbeusedtocontrolthemaximumcountervalue.WhenaCCRPcompare

matchoccursfromComparatorP,aPTMinterruptwillalsobegenerated.Countingthenumberof

overflowinterruptsignalsfromtheCCRPcanbeausefulmethodinmeasuringlongpulsewidths.

ThePTIO1andPTIO0bitscanselecttheactivetriggeredgeonthePTPIorPTCKpintobearising

edge,fallingedgeorbothedgetypes.IfthePTIO1andPTIO0bitsarebothsethigh,thennocapture

operationwilltakeplaceirrespectiveofwhathappensonthePTPIorPTCKpin,howeveritmustbe

notedthatthecounterwillcontinuetorun.

AsthePTPIorPTCKpinispinsharedwithotherfunctions,caremustbetakenifthePTMisinthe

InputCaptureMode.Thisisbecauseifthepinissetupasanoutput,thenanytransitionsonthispin

maycauseaninputcaptureoperationtobeexecuted.ThePTCCLR,PTOCandPTPOLbitsarenot

usedinthisMode.

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