Synchronization Output Signals - Analog Devices ADV7181BCP Manual

ADV7181B

SYNCHRONIZATION OUTPUT SIGNALS

HS Configuration
The following controls allow the user to configure the behavior
of the HS output pin only:
•
Beginning of HS signal via HSB[10:0]
•
End of HS signal via HSE[10:0]
•
Polarity of HS using PHS
The HS begin and HS end registers allow the user to freely
position the HS output (pin) within the video line. The values
in HSB[10:0] and HSE[10:0] are measured in pixel units from
the falling edge of HS. Using both values, the user can program
both the position and length of the HS output signal.
HSB[10:0] HS Begin, Address 0x34[6:4],
Address 0x35[7:0]
The position of this edge is controlled by placing a binary
number into HSB[10:0]. The number applied offsets the edge
with respect to an internal counter that is reset to 0 immediately
after EAV Code FF, 00, 00, XY (see Figure 19). HSB is set to
00000000010b, which is 2 LLC1 clock cycles from Count[0].
The default value of HSB[10:0] is 0x002, indicating that the HS
pulse starts two pixels after the falling edge of HS.
Table 54. HS Timing Parameters (see Figure 19)
HS Begin Adjust
(HSB[10:0])
Standard
(Default)
NTSC 00000000010b
NTSC Square Pixel 00000000010b
PAL 00000000010b
LLC1
PIXEL
Cr Y
BUS
ACTIVE
VIDEO
HS
D
E
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HS End Adjust
(HSE[10:0])
(Default)
00000000000b
00000000000b
00000000000b
FF 00 00 XY 80 10 80 10
EAV
HSE[10:0] HSB[10:0]
4 LLC1
HSE[10:0] HS End, Address 0x34[2:0], Address 0x36[7:0]
The position of this edge is controlled by placing a binary
number into HSE[10:0]. The number applied offsets the edge
with respect to an internal counter that is reset to 0 immediately
after EAV Code FF, 00, 00, XY (see Figure 19). HSE is set to
00000000000b, which is 0 LLC1 clock cycles from Count[0].
The default value of HSE[10:0] is 000, indicating that the HS
pulse ends zero pixels after a falling edge of HS.
For example
1. To shift the HS toward active video by 20 LLC1s, add
20 LLC1s to both HSB and HSE, that is, HSB[10:0] =
[00000010110], HSE[10:0] = [00000010100].
2. To shift the HS away from active video by 20 LLC1s, add
1696 LLC1s to both HSB and HSE (for NTSC), that is,
HSB[10:0] = [11010100010], HSE[10:0] = [11010100000].
1696 is derived from the NTSC total number of pixels =
1716.
To move 20 LLC1s away from active video is equal to subtracting
20 from 1716 and adding the result in binary to both HSB[10:0]
and HSE[10:0].
PHS Polarity HS, Address 0x37[7]
The polarity of the HS pin can be inverted using the PHS bit.
When PHS is 0 (default), HS is active high.
When PHS is 1, HS is active low.
Characteristic
HS to Active Video
(LLC1 Clock Cycles)
(C in Figure 19) (Default)
272
276
284
80 10 FF 00 00
H BLANK SAV
C
E
Figure 19. HS Timing
Rev. B | Page 38 of 100
Active Video
Samples/Line
(D in Figure 19)
720Y + 720C = 1440
640Y + 640C = 1280
720Y + 720C = 1440
XY Cb Y Cr Y Cb Y Cr
ACTIVE VIDEO
D
Total LLC1
Clock Cycles
(E in Figure 19)
1716
1560
1728