VS6663CC Datasheet, PDF (45/63 Pages) STMicroelectronics – 1.3 megapixel camera module

VS6663CC
Video timing
Table 25. Analog gain control (continued)
Gain value (0x0204/0x0205) Coarse gain code [A7:A4]
Coarse analog gain
0x0040
0100
2.5 dB (x1.33)
0x0050
0101
3.2 dB (x1.45)
0x0060
0x0070
0110
0111
4.1 dB (x1.60)
5.0 dB (x1.78)
0x0080
1000
6.0 dB(x2.00)
0x0090
1001
7.2 dB (x2.29)
0x00A0
1010
8.5 dB (x2.66)
0x00B0
0x00C0
1011
1100
10.1 dB (x3.20)
12.0 dB (x4.00)
0x00D0
1101
14.5 dB (x5.33)
0x00E0
1110
18.1 dB (x8.00)
0x00F0
1111
24.1 dB (x16.00)
6.3.2
6.3.3
Digital gain
To help compensate for the relatively coarse analogue gain steps, VS6663CC contains a
digital multiplier to “fill” in the missing steps. By mixing analogue and digital gain it is
possible to implement 3% gain steps across the full 1x to 16x gain range
The details of the digital gain implementation are listed below:
• four individual 16-bit digital channel gains - one per Bayer channel
– digital_gain_greenR (0x020E and 0x020F)
– digital_gain_red (0x0210 and 0x0211)
– digital_gain_blue (0x0212 and 0x0213)
– digital_gain_greenB (0x0214 and 0x0215)
• The digital gain range for each channel is 0.0039 to 1.996 in steps of 0.0039 (1/256)
– digital_gain_min {0x1084:0x1085} = 0x0001 (0.0039)
– digital_gain_max {0x1086:0x1087} = 0x01FF (1.996)
– digital_gain_step {0x1088:0x1089} = 0x0001 (0.0039)
Integration and gain parameter retiming
The modification of exposure parameter (coarse integration time or gain) register values
does not take effect immediately.
The exact time at which changes to certain parameters take effect is controlled both to
ensure that each frame of image data produced has consistent settings and that changes in
groups of related parameters can be synchronized.
To eliminate the possibility of the sensor array seeing only part of the new exposure and
gain setting, if the serial interface communications extends over a frame boundary, the
internal retiming of exposure and gain data is disabled while writing data to the serial
interface register map. Therefore if the 4 bytes of exposure and gain data is sent as an auto-
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