ov7620 OmniVision Technologies, Inc, ov7620 Datasheet - Page 40

• Manufacturer Part Number: ov7620
• Description: Single-chip Cmos Vga Color Digital Camera
• Manufacturer: OmniVision Technologies, Inc

OV7620/OV7120 Product Specifications - Rev. 1.2 (7/10/01)
Register 22- rw: U Channel Offset Adjustment
Register 23- rw: Crystal Current control.
Register 24- rw: AEW Auto Exposure White Pixel Ratio
Bits
Default
Bits
Default
Bits
Interlace
Progressive Scan
U
U7: Offset adjustment direction: 0 - Add U[6:0]; 1 -Subtract U[6:0].
If register 2D bit 0 = 0, this register has no function.
CC7 - CC6: Crystal amplifier current gain. (00) maximum current; (11) minimum current
CC5 ~ CC0: Reserved
Registers 24 and 25 together control the AEC target values for image brightness.
For a brighter image, increase register 24 and decrease register 25.
For a darker image, decrease register 24 and decrease reister 25.
AEW7-AEW0 - used to calculate the white pixel ratio. OV7620/OV7120 AEC algorithm counts the whole
Note: AEW<7:0> must combined with register [26] AEB<7:0>. Keep the relation always true: AEW<7:0> +
6-U0: U channel digital output offset adjustment. Range: +128mV ~ -128mV. If register 27 bit 2=0, this
CC7
U7
1
0
register will be updated by internal auto A/D BLC circuit, and write a value to this register with
SCCB has no effect. If register 27 bit 2=1, U channel offset adjustment will use the register
stored value which can be changed by SCCB. If register 26 bit 1=1, this register has no effect
to A/D output data. If output RGB raw data, this register will adjust R/G/B data.
field/frame white pixel (its luminance level is higher than a fixed level) and black pixel (its lumi-
nance level is lower than a fixed level) number. When white/black pixel ratio is same as the
ratio defined by registers [25] and [26], image stable. This register is used to define the white
pixel ratio, default is 25%, each LSB represent step: Interlaced: 1.3%; Progressive Scan:
0.7%. Change range is: Interlaced: [01] ~ [4A]; Progressive Scan: [01] ~ [96]. Increase
AEW<7:0> will increase the white pixel ratio. For same light condition, the image brightness
will increase if AEW<7:0> increase.
AEB<7:0> > [4A] for Interlaced; AEW<7:0> + AEB<7:0> > [90].
AEW7
0
0
CC6
U6
0
0
AEW6
0
0
CC5
U5
0
0
AEW5
0
0
CC4
U4
0
-
AEW4
Preliminary
0
1
CC3
U3
0
-
AEW3
1
0
CC2
U2
0
-
Company Confidential
OMNIVISION TECHNOLOGIES INC.
AEW2
0
0
CC1
U1
0
-
AEW1
0
0
CC0
U0
0
-
AEW0
0
0