HT69F360 datasheet(174/235 Pages) HOLTEK

174 / 235 page

Rev. 1.30

174

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Rev. 1.30

175

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HT69F340/HT69F350/HT69F360

TinyPowerTM I/O Flash MCU with LCD & EEPROM

HT69F340/HT69F350/HT69F360

TinyPowerTM I/O Flash MCU with LCD & EEPROM

Theread-onlyTXIFflagissetbytheUARThardwareandifsetindicatesthattheTXRregisteris

emptyandthatotherdatacannowbewrittenintotheTXRregisterwithoutoverwritingtheprevious

data.IftheTEIEbitissetthentheTXIFflagwillgenerateaninterrupt.

Duringadatatransmission,awriteinstructiontotheTXRregisterwillplacethedataintotheTXR

isnodatatransmissioninprogress,awriteinstructiontotheTXRregisterwillplacethedatadirectly

intotheshiftregister,resultinginthecommencementofdatatransmission,andtheTXIFbitbeing

immediatelyset.Whenaframetransmissioniscomplete,whichhappensafterstopbitsaresent

orafterthebreakframe,theTIDLEbitwillbeset.TocleartheTIDLEbitthefollowingsoftware

sequenceisused:

1.AUSRregisteraccess

2.ATXRregisterwriteexecution

NotethatboththeTXIFandTIDLEbitsareclearedbythesamesoftwaresequence.

Transmit break

IftheTXBRKbitissetthenbreakcharacterswillbesentonthenexttransmission.Breakcharacter

transmissionconsistsofastartbit,followedby13×N"0"bitsandstopbits,whereN=1,2,etc.Ifa

breakcharacteristobetransmittedthentheTXBRKbitmustbefirstsetbytheapplicationprogram,

thenclearedtogeneratethestopbits.Transmittingabreakcharacterwillnotgenerateatransmit

interrupt.Notethatabreakconditionlengthisatleast13bitslong.IftheTXBRKbitiscontinually

keptatalogichighlevelthenthetransmittercircuitrywilltransmitcontinuousbreakcharacters.

AftertheapplicationprogramhasclearedtheTXBRKbit,thetransmitterwillfinishtransmittingthe

lastbreakcharacterandsubsequentlysendoutoneortwostopbits.Theautomaticlogichighsatthe

endofthelastbreakcharacterwillensurethatthestartbitofthenextframeisrecognized.

UART receiver

TheUARTiscapableofreceivingwordlengthsofeither8or9bits.IftheBNObitisset,theword

lengthwillbesetto9bitswiththeMSBbeingstoredintheRX8bitoftheUCR1register.Atthe

receivercoreliestheReceiveSerialShiftRegister,commonlyknownastheRSR.Thedatawhich

isreceivedontheRXexternalinputpin,issenttothedatarecoveryblock.Thedatarecoveryblock

operatingspeedis16timesthatofthebaudrate,whilethemainreceiveserialshifteroperatesatthe

baudrate.AftertheRXpinissampledforthestopbit,thereceiveddatainRSRistransferredtothe

receivedataregister,iftheregisterisempty.ThedatawhichisreceivedontheexternalRXinputpin

issampledthreetimesbyamajoritydetectcircuittodeterminethelogiclevelthathasbeenplaced

ontotheRXpin.ItshouldbenotedthattheRSRregister,unlikemanyotherregisters,isnotdirectly

mappedintotheDataMemoryareaandassuchisnotavailabletotheapplicationprogramfordirect

read/writeoperations.

Receiving data

WhentheUARTreceiverisreceivingdata,thedataisseriallyshiftedinontheexternalRXinput

pin,LSBfirst.Inthereadmode,theRXRregisterformsabufferbetweentheinternalbusandthe

receivershiftregister.TheRXRregisterisatwobytedeepFIFOdatabuffer,wheretwobytescan

beheldintheFIFOwhileathirdbytecancontinuetobereceived.Notethattheapplicationprogram

mustensurethatthedataisreadfromRXRbeforethethirdbytehasbeencompletelyshifted

in,otherwisethisthirdbytewillbediscardedandanoverrunerrorOERRwillbesubsequently

indicated.Thestepstoinitiateadatatransfercanbesummarizedasfollows:

• MakethecorrectselectionofBNO,PRT,PRENandSTOPSbitstodefinethewordlength,parity

typeandnumberofstopbits.

HT69F360 датащи(PDF) 174 Page - Holtek Semiconductor Inc

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