NTSC COMPOSITE
VIDEO
BOTTOM I
OF
FIELD
2
6
EQUAL
I
ZINC
PULSES
6
SERRATED
PULSES
6
EQUALIZING
PULSES
Video Option
RETRACE I TOP
BLANKING
OF
FIELD
1
~
I-
s2
s-i-
1
-1-
2
-1-
3
-f-
4
-f-
s
-+-
6
-+-
7
-f-
s
-+-
9
-+-
10-!
I-
22-j
PLL
VCO
OUT
HCLK
VERTICAL
SYNC
BOTTOM
I
OF
FIELD
1
6
EQUALIZING
PULSES
FIELD
1
6
SERRATED
PULSES
6
EQUALIZING
PULSES
RETRACE I TOP
BLANKING
OF
FIELD
2
~
I-
263-+- 1
-+-
2
-+--
3
-+-
4
-+-
5
-+-
6 -+ 7
-+--
8
-+--
9
-1-
10
-I
I-
22-j
PLL
VCO
OUT
HCLK
VERTICAL
SYNC
2212 Service Manual
FIELD
2
Figure 3-9: Timing Diagram from Composite Sync to Trigger Signal
02703B preloads
the
line selector counter (02709,
02710,
02711)
with
the
value as written
in
the
control register (02706, 02707)
by
the
main
controller.
The preload value reflects the line
number
that is selected to trigger on.
The
line
selector counts up, clocked by
HORIZCLK_O
and
produces a
RCO.
If TV
_EN_O
is valid,
ALL_LINES
is
not
valid, UNLOCKED is
not
valid,
and
RCO
is valid,
then
the combinatorial logic inside
02708
creates a trigger
pulse
from
CMPSS (or
HCLK
after a small delay).
Revised 3/93
3-
39
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