Analog Devices ADV7610 Hardware User's Manual page 108

UG-438
Manual Gain Filter Mode
The ADV7610 provides a special filter option for the manual gain mode. This is functional only when manual gain is enabled. The
purpose of this filter is a smoothing mechanism when the manual gain value is updated continuously by an external system based on
either external or readback conditions in the ADV7610. The filter designed is an IIR filter with a transfer function of the form:
YN = (1 − A) × YN − 1 + A × XN
where A is the filter coefficient.
The values possible for A can vary from 1 (no filtering) to 1/128K (K = 1024). The value of coefficient A is chosen by programming
CP_GAIN_FILT[3:0].
CP_GAIN_FILT[3:0], Addr 44 (CP), Address 0x84[7:4]
A control to set the coefficient A of the IIF filter to filter the gain applied to the video signal when the gain is manually set. The value set
in this register is effective only when manual gain is enabled. The filter is designed as an IIR filter with a transfer function of the form
Y[N] = (1 − A) × y[N − 1] + A × X[N]
Function
CP_GAIN_FILT[3:0]
0000 (default)
0001
0010
0011
0100
0101
0110
0111
1000
1001
1010
1011
All other values
Other Gain Controls
OP_656_RANGE, IO, Address 0x02[2]
A control to set the output range of the digital data. It also automatically the data saturator setting.
Function
OP_656_RANGE
0 (default)
1
Table 43. OP_656_RANGE Description for HDMI Receiver Input Mode
Input Range
0 to 255
16 to 235
Table 44. OP_656_RANGE Description for Analog Front-End Input Mode
OP_656_RANGE
0 (0 to 255 output)
1 (16 to 235 RGB output, 16 to 240 CrCb output)
Description
No filtering, that is, coefficient A = 1.
Coefficient A = 1/128 lines.
Coefficient A = 1/256 lines.
Coefficient A = 1/512 lines.
Coefficient A = 1/1024 lines.
Coefficient A = 1/2048 lines.
Coefficient A = 1/4096 lines.
Coefficient A = 1/8192 lines.
Coefficient A = 1/16,384 lines.
Coefficient A = 1/32,768 lines.
Coefficient A = 1/65,536 lines.
Coefficient A = 1/131,072 lines.
Reserved. Do not use.
Description
Enables full output range (0 to 255)
Enables limited output range (16 to 235)
OP_656_RANGE
0 (0 to 255 output)
1 (16 to 235 RGB output, 16 to 240 CrCb output)
0 (0 to 255 output)
1 (16 to 235 RGB output, 16 to 240 CrCb output)
Rev. 0 | Page 108 of 184
Hardware User Guide
Gain
1
(235 − 16)/255 = 0.859
255/(235 − 16) = 1.164
1
Gain
(255 − 0 + 1) × 16/1792 = 2.29
(235 − 16 + 1) × 16/1792 = 1.96