Holtek HT66F20 - Page 224

Rev. 2.50 224 June 22, 2017 Rev. 2.50 225 June 22, 2017
HT66F20/HT66F30/HT66F40/HT66F50/HT66F60
HT66FU30/HT66FU40/HT66FU50/HT66FU60
A/D Flash MCU with EEPROM
HT66F20/HT66F30/HT66F40/HT66F50/HT66F60
HT66FU30/HT66FU40/HT66FU50/HT66FU60
A/D Flash MCU with EEPROM
LVD Interrupt
TheLowVoltageDetectorInterruptiscontainedwithintheMulti-functionInterrupt.AnLVD
InterruptrequestwilltakeplacewhentheLVDInterruptrequestflag,LVF,isset,whichoccurs
whentheLowVoltageDetectorfunctiondetectsalowpowersupplyvoltage.Toallowtheprogram
tobranchtoitsrespectiveinterruptvectoraddress,theglobalinterruptenablebit,EMI,LowVoltage
Interruptenablebit,LVE,andassociatedMulti-functioninterruptenablebit,mustrstbeset.When
theinterruptisenabled,thestackisnotfullandalowvoltageconditionoccurs,asubroutinecallto
theMulti-functionInterruptvector,willtakeplace.WhentheLowVoltageInterruptisserviced,the
EMIbitwillbeautomaticallyclearedtodisableotherinterrupts,howeveronlytheMulti-function
interruptrequestagwillbealsoautomaticallycleared.AstheLVFagwillnotbeautomatically
cleared,ithastobeclearedbytheapplicationprogram.
TM Interrupts
TheCompactandStandardTypeTMshavetwointerruptseach,whiletheEnhancedTypeTMhas
threeinterrupts.AlloftheTMinterruptsarecontainedwithintheMulti-functionInterrupts.Foreach
oftheCompactandStandardTypeTMstherearetwointerruptrequestagsTnPFandTnAFand
twoenablebitsTnPEandTnAE.FortheEnhancedTypeTMtherearethreeinterruptrequestags
TnPF,TnAFandTnBFandthreeenablebitsTnPE,TnAEandTnBE.ATMinterruptrequestwill
takeplacewhenanyoftheTMrequestagsareset,asituationwhichoccurswhenaTMcomparator
P,AorBmatchsituationhappens.
Toallowtheprogramtobranchtoitsrespectiveinterruptvectoraddress,theglobalinterruptenable
bit,EMI,respectiveTMInterruptenablebit,andrelevantMulti-functionInterruptenablebit,MFnE,
mustrstbeset.Whentheinterruptisenabled,thestackisnotfullandaTMcomparatormatch
situationoccurs,asubroutinecalltotherelevantMulti-functionInterruptvectorlocations,willtake
place.WhentheTMinterruptisserviced,theEMIbitwillbeautomaticallyclearedtodisableother
interrupts,howeveronlytherelatedMFnFagwillbeautomaticallycleared.AstheTMinterrupt
requestagswillnotbeautomaticallycleared,theyhavetobeclearedbytheapplicationprogram.