EVAL-ADV7183BEB View Datasheet(PDF) - Analog Devices
Part Name
Description
MFG CO.
'EVAL-ADV7183BEB' PDF : 104 Pages View PDF
CG[11:0] Chroma Gain, Address 0x2D [3:0];
Address 0x2E [7:0] CMG[11:0]
Chroma Manual Gain, Address 0x2D [3:0];
Address 0x2E [7:0]
Chroma gain [11:0] is a dual-function register:
• If written to, a desired manual chroma gain can be
programmed. This gain becomes active if the CAGC[1:0]
mode is switched to manual fixed gain.
• Refer to Equation 2 for calculating a desired gain.
• If read back, this register returns the current gain value.
Depending on the setting in the CAGC[1:0] bits, this will
be one of the following values:
o Chroma manual gain value (CAGC[1:0] set to chroma
manual gain mode).
o Chroma automatic gain value (CAGC[1:0] set to any
of the automatic modes).
Table 72. CG/CMG Function
CG[11:0]/CMG[11:0] Read/Write
CMG[11:0]
Write
CG[11:0]
Read
Description
Manual gain for chroma
path.
Currently active gain.
Chroma _ Gain = (0 < CG ≤ 4095) = 0...4
(2)
1024
Example
Freezing the automatic gain loop and reading back the
CG[11:0] register results in a value of 0x47A.
1. Convert the read back value to decimal:
0x47A = 1146d
2. Apply Equation 2 to convert the readback value:
1146/1024 = 1.12
ADV7183A
CKE Color Kill Enable, Address 0x2B [6]
The Color Kill Enable bit allows the optional color kill function
to be switched on or off.
For QAM based video standards (PAL and NTSC) as well as FM
based systems (SECAM), the threshold for the color kill decision
is selectable via the CKILLTHR[2:0] bits.
If color kill is enabled, and if the color carrier of the incoming
video signal is less than the threshold for 128 consecutive video
lines, color processing is switched off (black and white output).
To switch the color processing back on, another 128 consecutive
lines with a color burst greater than the threshold are required.
The color kill option only works for input signals with a modu-
lated chroma part. For component input (YPrPb), there is no
color kill.
Table 73. CKE Function
CKE
Description
0
Color kill disabled.
1 (default) Color kill enabled.
CKILLTHR[2:0] Color Kill Threshold, Address 0x3D [6:4]
The CKILLTHR[2:0] bits allow the user to select a threshold for
the color kill function. The threshold only applies to QAM
based (NTSC and PAL) or FM modulated (SECAM) video
standards.
To enable the color kill function, the CKE bit must be set. For
settings 000, 001, 010, and 011, chroma demodulation inside
the ADV7183A may not work satisfactorily for poor input video
signals.
Table 74. CKILLTHR Function
Description
CKILLTHR[2:0] SECAM
NTSC, PAL
000
No color kill
Kill at < 0.5%
001
Kill at < 5%
Kill at < 1.5%
010
Kill at < 7%
Kill at < 2.5%
011
Kill at < 8%
Kill at < 4.0%
100 (default) Kill at < 9.5%
Kill at < 8.5%
101
Kill at < 15%
Kill at < 16.0%
110
Kill at < 32%
Kill at < 32.0%
111
Reserved for ADI internal use only. Do not
select.
Rev. B | Page 35 of 104
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