HT45F39 datasheet(44/102 Pages) HOLTEK

44 / 102 page

Rev. 1.10

July 01, 2016

Rev. 1.10

July 01, 2016

HT45F39/HT45F391

Ultrasonic Distance Measurement 8-bit Flash MCU

HT45F39/HT45F391

Ultrasonic Distance Measurement 8-bit Flash MCU

Programming Considerations

Withintheuserprogram,oneofthefirstthingstoconsiderisportinitialisation.Afterareset,allof

theI/Odataandportcontrolregisterswillbesethigh.ThismeansthatallI/Opinswilldefaultto

aninputstate,thelevelofwhichdependsontheotherconnectedcircuitryandwhetherpull-high

selectionshavebeenchosen.Iftheportcontrolregisters,PAC~PBC,arethenprogrammedtosetup

somepinsasoutputs,theseoutputpinswillhaveaninitialhighoutputvalueunlesstheassociated

portdataregisters,PA~PB,arefirstprogrammed.Selectingwhichpinsareinputsandwhichare

outputscanbeachievedbyte-widebyloadingthecorrectvaluesintotheappropriateportcontrol

registerorbyprogrammingindividualbitsintheportcontrolregisterusingthe"SET[m].i"and

CLR[m].i"instructions.Notethatwhenusingthesebitcontrolinstructions,aread-modify-write

operationtakesplace.Themicrocontrollermustfirstreadinthedataontheentireport,modifyitto

therequirednewbitvaluesandthenrewritethisdatabacktotheoutputports.

PortAhastheadditionalcapabilityofprovidingwake-upfunctions.Whenthedevicesareinthe

SLEEPMode,variousmethodsareavailabletowakethedevicesup.Oneoftheseisahightolow

transitionofanyofthePortApins.SingleormultiplepinsonPortAcanbesetuptohavethis

function.Inaddition,thePORTApinsalsoprovideOpenDrainI/Ostructureoptionswhichcanbe

controlledbythespecificregister.

Generic Input/Output Structure

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