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HT69F360 数据表(PDF) 174 Page - Holtek Semiconductor Inc |
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HT69F360 数据表(HTML) 174 Page - Holtek Semiconductor Inc |
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174 / 235 page ![]() Rev. 1.30 174 �ove��e� 1�� �01� Rev. 1.30 175 �ove��e� 1�� �01� 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 register,whichwillbecopiedtotheshiftregisterattheendofthepresenttransmission.Whenthere 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. |
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