HT45F12
8-Bit Flash MCU with Op Amps & Comparators
Programming Considerations
Withinꢀtheꢀuserꢀprogram,ꢀoneꢀofꢀtheꢀfirstꢀthingsꢀtoꢀconsiderꢀisꢀportꢀinitialisation.ꢀAfterꢀaꢀreset,ꢀallꢀofꢀ
theꢀI/Oꢀdataꢀandꢀportꢀcontrolꢀregistersꢀwillꢀbeꢀsetꢀhigh.ꢀThisꢀmeansꢀthatꢀallꢀI/Oꢀpinsꢀwillꢀdefaultꢀtoꢀ
anꢀinputꢀstate,ꢀtheꢀlevelꢀofꢀwhichꢀdependsꢀonꢀtheꢀotherꢀconnectedꢀcircuitryꢀandꢀwhetherꢀpull-highꢀ
selectionsꢀhaveꢀbeenꢀchosen.ꢀIfꢀtheꢀportꢀcontrolꢀregisters,ꢀPAC~PCC,ꢀareꢀthenꢀprogrammedꢀtoꢀsetupꢀ
someꢀpinsꢀasꢀoutputs,ꢀtheseꢀoutputꢀpinsꢀwillꢀhaveꢀanꢀinitialꢀhighꢀoutputꢀvalueꢀunlessꢀtheꢀassociatedꢀ
portꢀdataꢀregisters,ꢀPA~PC,ꢀareꢀfirstꢀprogrammed.ꢀSelectingꢀwhichꢀpinsꢀareꢀinputsꢀandꢀwhichꢀareꢀ
outputsꢀcanꢀbeꢀachievedꢀbyte-wideꢀbyꢀloadingꢀtheꢀcorrectꢀvaluesꢀintoꢀtheꢀappropriateꢀportꢀcontrolꢀ
registerꢀorꢀbyꢀprogrammingꢀindividualꢀbitsꢀinꢀtheꢀportꢀcontrolꢀregisterꢀusingꢀtheꢀ“SETꢀ[m].i”ꢀandꢀ
“CLRꢀ[m].i”ꢀinstructions.ꢀNoteꢀthatꢀwhenꢀusingꢀtheseꢀbitꢀcontrolꢀinstructions,ꢀaꢀread-modify-writeꢀ
operationꢀtakesꢀplace.ꢀTheꢀmicrocontrollerꢀmustꢀfirstꢀreadꢀinꢀtheꢀdataꢀonꢀtheꢀentireꢀport,ꢀmodifyꢀitꢀtoꢀ
theꢀrequiredꢀnewꢀbitꢀvaluesꢀandꢀthenꢀrewriteꢀthisꢀdataꢀbackꢀtoꢀtheꢀoutputꢀports.
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Read Modify Write Timing
PortꢀAꢀhasꢀtheꢀadditionalꢀcapabilityꢀofꢀprovidingꢀwake-upꢀfunctions.ꢀWhenꢀtheꢀdeviceꢀisꢀinꢀtheꢀ
SLEEPꢀorꢀIDLEꢀMode,ꢀvariousꢀmethodsꢀareꢀavailableꢀtoꢀwakeꢀtheꢀdeviceꢀup.ꢀOneꢀofꢀtheseꢀisꢀaꢀhighꢀ
toꢀlowꢀtransitionꢀofꢀanyꢀofꢀtheꢀPortꢀAꢀpins.ꢀSingleꢀorꢀmultipleꢀpinsꢀonꢀPortꢀAꢀcanꢀbeꢀsetupꢀtoꢀhaveꢀthisꢀ
function.ꢀInꢀaddition,ꢀtheꢀPortꢀBꢀpinsꢀalsoꢀprovideꢀOpenꢀDrainꢀI/Oꢀstructureꢀoptionsꢀwhichꢀcanꢀbeꢀ
controlledꢀbyꢀtheꢀspecificꢀregister.
Timer/Event Counter
Theꢀprovisionꢀofꢀtimersꢀformꢀanꢀimportantꢀpartꢀofꢀanyꢀmicrocontroller,ꢀgivingꢀtheꢀdesignerꢀaꢀmeansꢀ
ofꢀcarryingꢀoutꢀtimeꢀrelatedꢀfunctions.ꢀTheꢀdeviceꢀcontainsꢀaꢀsigleꢀcount-upꢀtimerꢀofꢀ8-bitꢀcapacity.ꢀ
Asꢀtheꢀtimerꢀhasꢀthreeꢀdifferentꢀoperatingꢀmodes,ꢀitꢀcanꢀbeꢀconfiguredꢀtoꢀoperateꢀasꢀaꢀgeneralꢀtimer,ꢀ
anꢀexternalꢀeventꢀcounterꢀorꢀasꢀaꢀpulseꢀwidthꢀcaptureꢀdevice.ꢀTheꢀprovisionꢀofꢀanꢀinternalꢀprescalerꢀ
toꢀtheꢀclockꢀcircuitryꢀonꢀgivingꢀaddedꢀrangeꢀtoꢀtheꢀtimer.
ThereꢀareꢀtwoꢀtypesꢀofꢀregistersꢀrelatedꢀtoꢀtheꢀTimer/EventꢀCounter.ꢀTheꢀfirstꢀisꢀtheꢀregistersꢀthatꢀ
containꢀtheꢀactualꢀvalueꢀofꢀtheꢀTimer/EventꢀCounterꢀandꢀintoꢀwhichꢀanꢀinitialꢀvalueꢀcanꢀbeꢀpreloaded.ꢀ
ReadingꢀfromꢀtheseꢀregistersꢀretrievesꢀtheꢀcontentsꢀofꢀtheꢀTimer/EventꢀCounter.ꢀTheꢀsecondꢀtypeꢀ
ofꢀassociatedꢀregisterꢀisꢀtheꢀTimerꢀControlꢀRegisterꢀwhichꢀdefinesꢀtheꢀtimerꢀoptionsꢀandꢀdeterminesꢀ
howꢀtheꢀTimer/EventꢀCounterꢀisꢀtoꢀbeꢀused.ꢀTheꢀTimer/EventꢀCounterꢀcanꢀhaveꢀitsꢀclockꢀconfiguredꢀ
toꢀcomeꢀfromꢀanꢀinternalꢀclockꢀsource.ꢀInꢀaddition,ꢀitsꢀclockꢀsourceꢀcanꢀalsoꢀbeꢀconfiguredꢀtoꢀcomeꢀ
fromꢀanꢀexternalꢀtimerꢀpin.
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8-bit Timer/Event Counter Structure
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Note:ꢀTheꢀoutputꢀisꢀcontrolledꢀbyꢀPA5ꢀdata.
Rev. 0.00
5ꢅ
�eꢀteꢁꢂeꢃ ꢄꢅꢆ ꢄ01ꢄ
HOLTEK [ HOLTEK SEMICONDUCTOR INC ]
