adv7189b Analog Devices, Inc., adv7189b Datasheet - Page 32

• Manufacturer Part Number: adv7189b
• Description: Multiformat Sdtv Video Decoder
• Manufacturer: Analog Devices, Inc.

ADV7189B
For example, program the ADV7189B into manual fixed gain
mode with a desired gain of 0.89:
1.
2.
3.
4.
5.
BETACAM Enable Betacam Levels, Address 0x01[5]
If YPrPb data is routed through the ADV7189B, the automatic
gain control modes can target different video input levels, as
outlined in. Note the BETACAM bit is valid only if the input
mode is YPrPb (component). The BETACAM bit sets the target
value for AGC operation. A review of the following sections is
useful.
x
x
The automatic gain control (AGC) algorithms adjust the levels
based on the setting of the BETACAM bit. See
Table 37. BETACAM Function
BETACAM
0 (default)
1
Use Equation 1 to convert the gain:
0.89 × 2048 = 1822.72
Truncate to integer value:
1822.72 = 1822
Convert to hexadecimal:
1822d = 0x71E
Split into two registers and program:
Luma Gain Control 1[3:0] = 0x7
Luma Gain Control 2[7:0] = 0x1E
Enable Manual Fixed Gain Mode:
Set LAGC[2:0] to 000
I NSEL[3:0] Input Selection, Address 0x00[3:0] to find out
1 9 0 H
how component video (YPrPb) can be routed through the
ADV7189B.
V ideo Standard Selection to select the various standards,
1 9 1 H
for example, with and without pedestal.
Description
Assuming YPrPb is selected as input format.
Selecting PAL with pedestal selects MII.
Selecting PAL without pedestal selects SMPTE.
Selecting NTSC with pedestal selects MII.
Selecting NTSC without pedestal selects SMPTE.
Assuming YPrPb is selected as input format.
Selecting PAL with pedestal selects BETACAM.
Selecting PAL without pedestal selects BETACAM
variant.
Selecting NTSC with pedestal selects BETACAM.
Selecting NTSC without pedestal selects
BETACAM variant.
T able 37.
1 9 2 H
Rev. B | Page 32 of 104
Table 38. Betacam Levels
Name
Y
Range
U and
V
Range
Sync
Depth
PW_UPD Peak White Update, Address 0x2B[0]
The peak white and average video algorithms determine the
gain based on measurements taken from the active video. The
PW_UPD bit determines the rate of gain change. LAGC[2:0]
must be set to the appropriate mode to enable the peak white or
average video mode in the first place. For more information, refer
to the
0x2C[7:0] section.
Setting PW_UPD to 0 updates the gain once per video line.
Setting PW_UPD to 1 (default) updates the gain once per field.
Chroma Gain
CAGC[1:0] Chroma Automatic Gain Control,
Address 0x2C[1:0]
The two bits of color automatic gain control mode select
the basic mode of operation for automatic gain control in the
chroma path.
Table 39. CAGC Function
CAGC[1:0]
00
01
10 (default)
11
CAGT[1:0] Chroma Automatic Gain Timing,
Address 0x2D[7:6]
The chroma automatic gain timing register allows the user
to influence the tracking speed of the chroma automatic gain
control. This register has an effect only if the CAGC[1:0]
register is set to 10 (automatic gain).
Table 40. CAGT Function
CAGT[1:0]
00
01
10
11 (default)
L AGC[2:0] Luma Automatic Gain Control, Address
1 9 3 H
Betacam
(mV)
0 to 714
(incl. 7.5%
pedestal)
–467 to +467
286
Description
Manual fixed gain (use CMG[11:0]).
Use luma gain for chroma.
Automatic gain (based on color burst).
Freeze chroma gain.
Slow (TC = 2 sec)
Medium (TC = 1 sec)
Fast (TC = 0.2 sec)
Adaptive
Description
Betacam
Variant
(mV)
0 to 714
–505 to
+505
286
SMPTE
(mV)
0 to
700
–350
to
+350
300
MII (mV)
0 to 700 (incl.
7.5%
pedestal)
–324 to +324
300