Video Port/VCXO Interpolated Control (VIC) Port User's Guide

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Display Timing Examples
The interlaced BT.656 vertical output timing is shown in Figure 4-26 . The BT.656 active field 1 is 244-lines
high and active field 2 is 243-lines high. This example shows the 480-line image window centered in the
screen. This results in an IMGVOFF n of 3 lines and also results in a non-data line at the end of field 1 due
to its extra active line.
The VBLNK and VSYNC signals are shown as they would be output for active-low operation. Note that
only one of the two signals is actually available externally. The VBLNK and VSYNC edges for field 1 occur
at the end of an active line so their XSTART/XSTOP values are set to 720 (start of blanking). For field 2,
VBLNK and VSYNC edges occur during the middle of the active horizontal line so their XSTART/XSTOP
values are set to 360. Note that, from an analog standpoint, vertical blanking begins a half-line before
digital blanking so that VBLNKYSTART2 is set to 263 (with VBLNKXSTART2 set to 360) while VBITSET2
is programmed to 264. For true BT.656 operation, neither VBLNK nor VSYNC would be used.
The FLD output is setup to transition at the start of each analog field (start of vertical blanking). Since
EAV[F] transitions on lines 4 and 266, this requires programming FBITCLR to 4, FBITSET to 266,
FLD1YSTART to 1, and FLD2YSTART to 263. Note that FLD2XSTRT is 360 so that the field indicator
output changes halfway through the line.
The ILCOUNT operation follows the description in Section 4.1.2 . ILCOUNT resets to 1 at the first
displayed line (FLCOUNT = VBLNKSTOP x + IMGVOFF x) and stops counting at the last displayed pixel
(IPCOUNT = IMGVSIZE x). The operation during non-display time is not a requirement, it could continue
counting until the next FLCOUNT = VBLNKSTOP x + IMGVOFF x point or it could reset immediately after
IMGVSIZE x or when FLCOUNT is reset.
The active horizontal output column shows the output data during the active portion of the horizontal line.
It is assumed that the DVEN bit in VDCTL is set to enable the default output.
112 Video Display Port SPRUEM1 – May 2007
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