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4.2.2BlankingCodes
4.2.3BT.656ImageDisplay
4.2.4BT.656FIFOUnpacking
VDOUT[9−2]
VCLKOUT
63 5655 4847 4039 32
Y FIFO
Cb FIFO
Cb 0 Cr 0 Cb 1 Cr 1Y 0 Y 1 Y 2 Y 3 Cb 2 Cr 2Y 4 Y 5
Cr FIFO
Little-Endian Unpacking
31 2423 1615 8 7 0
Y 25
Y 17
Y 9
Y 1
Y 24
Y 16
Y 8
Y 0
Y 27
Y 19
Y 11
Y 3
Y 26
Y 18
Y 10
Y 2
Y 29
Y 21
Y 13
Y 5
Y 28
Y 20
Y 12
Y 4
Y 31
Y 23
Y 15
Y 7
Y 30
Y 22
Y 14
Y 6
63 5655 4847 4039 3231 2423 1615 8 7 0
Cb 9
Cb 1
Cb 8
Cb 0
Cb 11
Cb 3
Cb 10
Cb 2
Cb 13
Cb 5
Cb 12
Cb 4
Cb 15
Cb 7
Cb 14
Cb 6
63 5655 4847 4039 3231 2423 1615 8 7 0
Cr 9
Cr 1
Cr 8
Cr 0
Cr 11
Cr 3
Cr 10
Cr 2
Cr 13
Cr 5
Cr 12
Cr 4
Cr 15
Cr 7
Cr 14
Cr 6
BT.656VideoDisplayMode
ThetimebetweentheEAVandSAVcodeoneachlinerepresentsthehorizontalblankinginterval.During
thistime,thevideoportoutputsdigitalvideoblankingvalues.Thesevaluesare10.0hforluma(Y)
samplesand80.0hforchroma(Cb/Cr)samples.Thesevaluesarealsooutputduringtheactivelineperiod
ofverticalblanking(betweenSAVandEAVwhenV=1).Inaddition,iftheDVENbitinVDCTLiscleared
to0,theblankingvaluesareoutputduringtheportionofactivevideolinesthatarenotapartofthe
displayedimage.
ForBT.656displaymode,theFIFObufferisdividedintothreesections.OneFIFOis2560-bytesdeepand
isusedforthestorageofYoutputsamples;theothertwoFIFOsareeach1280-bytesdeepandare
dedicatedforstorageofCbandCrsamples.EachFIFOhasamemory-mappedlocationassociatedwith
it;YDST,CBDST,andCRDST.Thepseudo-registersarewrite-onlyandareusedbyEDMAstofillthe
FIFOswithoutputdata.ThevideodisplaymodulemultiplexesthedatafromthethreeFIFOstogenerate
theoutputCbYCrYdatastream.
Ifvideodisplayisenabled,thevideodisplaymoduleusestheYEVT,CbEVT,andCrEVTeventstonotify
theEDMAcontrollerthatdataneedstobeplacedintothedisplayFIFOs.Thenumberofpixelsrequiredto
generatetheeventsissetbythethresholdfieldbitsinVDTHRLDregister.Thevideodisplaymodule
generatestheeventsignalswhenthedisplaybufferholdslessthanthethresholdnumberofpixelsandthe
displayeventcounterhasnotexpired.OneveryYEVT,theEDMAshouldmovedatafromDSPmemoryto
theYbuffer,usingtheYFIFOdestinationregister(YDST)contentasthedestinationaddress.Onevery
CbEVT,theEDMAshouldmovedatafromDSPmemorytotheCbbuffer,usingtheCbFIFOdestination
register(CBDST)contentasthedestinationaddress.OneveryCrEVT,theEDMAshouldmovedatafrom
DSPmemorytotheCrbuffer,usingtheCrFIFOdestinationregister(CRDST)contentasthedestination
address.TheEDMAtransfersizefortheYbufferistwicethesizeoftheEDMAfortheCborCrbuffers.
DisplaydataisalwayspackedintotheFIFOsin64-bitwordsandmustbeunpackedbeforebeingsentto
thevideodisplaydatapipeline.Bydefault,dataisunpackedfromrighttoleft.
The8-bitBT.656modeusesthreeFIFOsforcolorseparation.Samplesareunpackedfromeachwordas
showninFigure4-12.
Figure4-12.8-BitBT.656FIFOUnpacking
SPRUEM1–May2007VideoDisplayPort101
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