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Field 1 Image Width
Field 1
Frame
Field 1 Image Horizontal Offset
Field 1 Image Height
Horizontal Blanking
Field 1 Vertical Blanking
Field 1 Image Vertical Offset
Field 1 Active Video
4.1.2VideoDisplayCounters
VideoDisplayModeSelection
Figure4-4.ProgressiveBlankingIntervalsandVideoArea
Togeneratetheimagetiming,thevideodisplaymoduleusesfivecounters:
•Framelinecounter(FLCOUNT)
•Framepixelcounter(FPCOUNT)
•Imagelinecounter(ILCOUNT)
•Imagepixelcounter(IPCOUNT)
•Videoclockcounter(VCCOUNT)
Theframelinecounter(FLCOUNT)countsthetotalnumberoflinesperframeincludingverticalblanking
intervals.Theframepixelcounter(FPCOUNT)countsthetotalnumberofpixelsperlineincluding
horizontalblankingintervals.FLCOUNTbeginscountingatthestartoftheverticalblankingintervalofthe
firstfield.FPCOUNTbeginscountingattheendofthehorizontalblankingintervalofeachline.Theyare
resetwhentheyreachtheirstopvaluesasspecifiedinthevideodisplayframesizeregister(VDFRMSZ).
Theimagelinecounter(ILCOUNT)andtheimagepixelcounter(IPCOUNT)trackthevisibleimagewithin
thefield.ILCOUNTbeginscountingatthefirstdisplayimagelineineachfield.IPCOUNTbeginscounting
atthefirstdisplayedimagepixeloneachline.Theystopcountingwhentheyreachtheimageheightand
imagewidthasspecifiedinthevideodisplayfieldnimagesizeregister(VDIMGSZn).
Thevideoclockcounter(VCCOUNT)countsVCLKINtransitionstodeterminewhentoincrement
FPCOUNTandIPCOUNTasdeterminedbythevideodisplaymode.InY/Cmode,FPCOUNTand
IPCOUNTincrementoneachVCLKINrisingedge.InBT.656mode,FPCOUNTandIPCOUNTincrement
oneveryotherVCLKINrisingedge.Inrawmode,FPCOUNTandIPCOUNTincrementonevery1to16
VCLKINcyclesasprogrammedbytheINCPIXbitsinthevideodisplaythresholdregister(VDTHRLD).
FPCOUNTandFLCOUNTarecomparedtovariousvaluestodeterminewhentoassertandnegate
variouscontrolsignals.The12-bitFPCOUNTisusedtodeterminewheretoenableanddisablehorizontal
syncandblankinginformationalongeachscanline.ThestateofFPCOUNTisreflectedintheVDXPOS
bitsofthevideodisplaystatusregister(VDSTAT).
96VideoDisplayPortSPRUEM1–May2007
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