Rev. 1.0, 02/00, page 773 of 1141
Csync
HVTH
SEPH
HHK
OSCH
HC
Digital H separation
counter
H complement and
mask counter
Forcible HHK
operation
Forcible HHK
operation
Comple-
ment
Comple-
ment
Comple-
ment
Comple-
ment
Comple-
ment
Comple-
ment
Figure 27.7 Timing of HHK Operation
When Complementary Pulses Inserted Three Successive Times While HHKON = 1
27.2.5
Vertical Sync Signal Threshold Register (VVTHR)
0
0
0
0
0
0
0
0
7
W
VVTH0
0
W
VVTH7
6
W
VVTH6
5
W
VVTH5
4
W
VVTH4
3
W
VVTH3
2
W
VVTH2
1
W
VVTH1
Bit :
Initial value :
R/W :
The VVTHR is an 8-bit write-only register for specifying the threshold value for the digital V
separation counter; this value is used to generate the SEPV signal from the Csync signal. The
SEPV signal is set to 1 when the digital V separation counter value matches the VVTHR value
while the Csync is high, and reset to 0 when the digital V separation counter value becomes 00
while the Csync is low. Set the VVTHR value so that the SEPV signal goes high 1/2H or more
after the Vsync start point. When reset, the VVTHR is initialized to H'E0.
Figure 27.8 shows the VVTHR value and the SEPV signal generation timing.
Csync
1/2 H or more
VVTH
H
SEPV
Digital V separation
counter
Figure 27.8 VVTHR Value and SEPV Generation Timing