HT66F20 datasheet(167/298 Pages) HOLTEK

167 / 298 page

Rev. 1.90

166

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Rev. 1.90

167

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HT66F20/HT66F30/HT66F40/HT66F50/HT66F60

HT66FU30/HT66FU40/HT66FU50/HT66FU60

Enhanced A/D Flash Type 8-Bit MCU with EEPROM

HT66F20/HT66F30/HT66F40/HT66F50/HT66F60

HT66FU30/HT66FU40/HT66FU50/HT66FU60

Enhanced A/D Flash Type 8-Bit MCU with EEPROM

Capture Input Mode

ToselectthismodebitsTnAM1,TnAM0andTnBM1,TnBM0intheTMnC1andTMnC2registers

shouldbesetto01respectively.Thismodeenablesexternalsignalstocaptureandstorethe

presentvalueoftheinternalcounterandcanthereforebeusedforapplicationssuchaspulsewidth

measurements.TheexternalsignalissuppliedontheTPnAandTPnB_0,TPnB_1,TPnB_2pins,

whoseactiveedgecanbeeitherarisingedge,afallingedgeorbothrisingandfallingedges;the

activeedgetransitiontypeisselectedusingtheTnAIO1,TnAIO0andTnBIO1,TnBIO0bitsinthe

TMnC1andTMnC2registers.ThecounterisstartedwhentheTnONbitchangesfromlowtohigh

whichisinitiatedusingtheapplicationprogram.

WhentherequirededgetransitionappearsontheTPnAandTPnB_0,TPnB_1,TPnB_2pinsthe

presentvalueinthecounterwillbelatchedintotheCCRAandCCRBregistersandaTMinterrupt

generated.IrrespectiveofwhateventsoccurontheTPnAandTPnB_0,TPnB_1,TPnB_2pins

thecounterwillcontinuetofreerununtiltheTnONbitchangesfromhightolow.WhenaCCRP

comparematchoccursthecounterwillresetbacktozero;inthiswaytheCCRPvaluecanbeused

tocontrolthemaximumcountervalue.WhenaCCRPcomparematchoccursfromComparatorP,

aTMinterruptwillalsobegenerated.Countingthenumberofoverflowinterruptsignalsfromthe

CCRPcanbeausefulmethodinmeasuringlongpulsewidths.TheTnAIO1,TnAIO0andTnBIO1,

TnBIO0bitscanselecttheactivetriggeredgeontheTPnAandTPnB_0,TPnB_1,TPnB_2pins

tobearisingedge,fallingedgeorbothedgetypes.IftheTnAIO1,TnAIO0andTnBIO1,TnBIO0

bitsarebothsethigh,thennocaptureoperationwilltakeplaceirrespectiveofwhathappensonthe

TPnAandTPnB_0,TPnB_1,TPnB_2pins,howeveritmustbenotedthatthecounterwillcontinue

torun.

AstheTPnAandTPnB_0,TPnB_1,TPnB_2pinsarepinsharedwithotherfunctions,caremust

betakeniftheTMisintheCaptureInputMode.Thisisbecauseifthepinissetupasanoutput,

thenanytransitionsonthispinmaycauseaninputcaptureoperationtobeexecuted.TheTnCCLR,

TnAOC,TnBOC,TnAPOLandTnBPOLbitsarenotusedinthismode.

HT66F20 Datasheet(PDF) 167 Page - Holtek Semiconductor Inc