HT45F65 datasheet(200/231 Pages) HOLTEK

200 / 231 page

Rev. 1.60

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HT45F65/HT45F66/HT45F67

Glucose Meter 8-Bit Flash MCU

Managing Receiver Errors

SeveraltypesofreceptionerrorscanoccurwithintheUARTmodule,thefollowingsectiondescribes

thevarioustypesandhowtheyaremanagedbytheUART.

Overrun Error – OERR

TheRXRregisteriscomposedofafourbytedeepFIFOdatabuffer,wherefourbytescanbeheldin

theFIFOregister,whilea5thbytecancontinuetobereceived.Beforethe5thbytehasbeenentirely

shiftedin,thedatashouldbereadfromtheRXRregister.Ifthisisnotdone,theoverrunerrorflag

OERRwillbeconsequentlyindicated.

Intheeventofanoverrunerroroccurring,thefollowingwillhappen:

• TheOERRflagintheUSRregisterwillbeset.

• TheRXRcontentswillnotbelost.

• Theshiftregisterwillbeoverwritten.

• AninterruptwillbegeneratediftheRIEbitisset.

TheOERRflagcanbeclearedbyanaccesstotheUSRregisterfollowedbyareadtotheRXR

Noise Error – NF

Over-samplingisusedfordatarecoverytoidentifyvalidincomingdataandnoise.Ifnoiseis

detectedwithinaframe,thefollowingwilloccur:

• Thereadonlynoiseflag,NF,intheUSRregisterwillbesetontherisingedgeoftheRXIFbit.

• DatawillbetransferredfromtheshiftregistertotheRXRregister.

• Nointerruptwillbegenerated.HoweverthisbitrisesatthesametimeastheRXIFbitwhich

itselfgeneratesaninterrupt.

NotethattheNFflagisresetbyaUSRregisterreadoperationfollowedbyanRXRregisterread

operation.

Framing Error – FERR

Thereadonlyframingerrorflag,FERR,intheUSRregister,issetifazeroisdetectedinsteadof

stopbits.Iftwostopbitsareselected,bothstopbitsmustbehigh.OtherwisetheFERRflagwillbe

set.TheFERRflagisbufferedalongwiththereceiveddataandisclearedinanyreset.

Parity Error – PERR

Thereadonlyparityerrorflag,PERR,intheUSRregister,issetiftheparityofthereceivedword

isincorrect.Thiserrorflagisonlyapplicableiftheparityfunctionisenabled,PREN=1,andifthe

paritytype,oddoreven,isselected.ThereadonlyPERRflagisbufferedalongwiththereceived

databytes.Itisclearedonanyreset,itshouldbenotedthattheFERRandPERRflagsarebuffered

alongwiththecorrespondingwordandshouldbereadbeforereadingthedataword.

HT45F65 Datasheet(PDF) 200 Page - Holtek Semiconductor Inc