
ADV7180
Rev. A | Page 92 of 112
Bits (Shading Indicates Default
State)
6
5
4
x
x
x
Comments
Subaddress
0x9B
Register
Letterbox 1
(Read Only)
Bit Description
LB_LCT[7:0]. Letterbox
data register.
7
x
3
x
2
x
1
x
0
x
LQFP-64
Reports the number of
black lines detected at the
top of active video
Reports the number of
black lines detected in the
bottom half of active video
if subtitles are detected
Reports the number of
black lines detected at the
bottom of active video
Set as default
Turn off CRC check
CGMSD goes high with
valid checksum
LFCSP-40
Notes
This feature examines the
active video at the start
and end of each field; it
enables format detection
even if the video is not
accompanied by a CGMS
or WSS sequence
0x9C
Letterbox 2
(Read Only)
LB_LCM[7:0]. Letterbox
data register.
x
x
x
x
x
x
x
x
0x9D
Letterbox 3
(Read Only)
LB_LCB[7:0]. Letterbox
data register.
x
x
x
x
x
x
x
x
Reserved.
CRC_ENABLE. Enable
CRC checksum
decoded from CGMS
packet to validate
CGMSD.
Reserved.
MUX_0[3:0]. Manual
muxing control for
MUX0.
This setting controls
which input is routed
to the ADC for
processing.
0
1
0
0
0xB2
CRC Enable
(Write Only)
0
0
0
1
0
0
0
0
0
1
1
1
1
0
0
0
0
1
1
0
0
1
1
0
1
0
1
0
1
0
1
0
1
0
1
0
0
0
0
0
0
1
1
1
1
0
0
0
0
1
1
1
1
0
0
1
1
0
0
1
1
0
0
1
1
0
0
1
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
Set as default
No connect
A
IN
1
A
IN
2
A
IN
3
A
IN
4
A
IN
5
A
IN
6
No connect
No connect
No connect
No connect
A
IN
3
A
IN
4
A
IN
5
A
IN
6
No connect
No connect
No connect
A
IN
2
No connect
No connect
A
IN
5
A
IN
6
No connect
Disable
Enable
MAN_MUX_EN = 1
No connect
A
IN
1
No connect
No connect
A
IN
2
A
IN
3
No connect
No connect
No connect
No connect
No connect
No connect
A
IN
2
A
IN
3
No connect
No connect
No connect
No connect
No connect
No connect
No connect
A
IN
3
No connect
No connect
Reserved.
MUX_1[3:0]. Manual
muxing control for
MUX1.
This setting controls
which input is routed
to the ADC for
processing.
0xC3
ADC SWITCH 1
Reserved.
MUX_2[3:0]. Manual
muxing control for
MUX2.
This setting controls
which input is routed
to the ADC for
processing.
MAN_MUX_EN = 1
MAN_MUX_EN = 1
Reserved.
MAN_MUX_EN. Enable
manual setting of the
input signal muxing.
LB_TH [4:0]. Sets the
threshold value that
determines if a line is
black.
Reserved.
LB_EL[3:0]. Programs
the end line of the
activity window for LB
detection (end of field).
LB_SL[3:0]. Program
the start line of the
activity window for LB
detection (start of
field).
This bit must be set to 1 for
manual muxing
0xC4
ADC Switch 2
0
1
1
0
0
Default threshold for the
detection of black lines
0xDC
Letterbox Control 1
1
0
1
1
1
0
0
Set as default
LB detection ends with the
last line of active video on a
field, 1100b: 262/525
0xDD
Letterbox Control 2
0
1
0
0
Letterbox detection aligned
with the start of active video,
0100b: 23/286 NTSC