VV5801B001 Ver la hoja de datos (PDF) - Vision
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VV5801B001 Datasheet PDF : 23 Pages
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VISION VV6801/5801 PRELIMINARY CUSTOMER DATASHEET Rev 1.1
Video modes.
Note: This method does not cancel dark current FPN, and as the pixel is reset twice, has two lots of ‘reset’
noise sources.
The array is released from reset by taking the input to the reset vertical shift registers, FI, high. The system
controlling the camera must then wait for 1306 lines to allow this “integrate wavefront” to propagate through
the shift register, before opening the shutter (or further extending the FI pulse). After the sensor has been
exposed for the appropriate time, FR must be pulsed high for 2 lines to read the pixel array and obtain the
exposed image data, which is loaded into the Line Buffer line by line.
When a line of 1028 pixels of image data has been read, the CDSR signal is pulsed high to reset the line of
pixels to Black (without advancing the HSR). COLSam is then pulsed to resample the row, and as each pixel
is read out this ‘Black Offset’ value is subtracted from the value stored in the line buffer and the result passed
on as corrected image data.
Note: During the 1280-line image data readout, LCK and EVEN must be at least twice their minimum periods
(with maximum PCK rate of 5.0MHz), to allow for the second line read.
y LCK
r EVEN
a CDSR
COLsam
in FI
FR
AVO
lim 1306 Lines
Exposure
AVO Not Valid
Black Ref Line
1306 Lines
Read Image & Offsets
Read Image
Read Black Offset
Pre Figure 5.3 : Relative timing for Correlated Double Sampling (CDS)
(See Section 7.5 for the exact relationships, and also how CDSR, COLSam and PXRD should inter-
act.)
5.3 Live-Video Mode
In the ‘Live Video’ mode the effect is similar to a conventional video camera, with a frame readout rate of just
under five frames/second (with a 5 MHz pixel clock) at full resolution. This could be used, for example, to
provide a moving ‘viewfinder’ display for a stills camera, however for achieving faster frame readout rates,
see Section 5.4.
In Live-Video mode the exposure level for a frame is controlled electronically by varying the high duration of
the FI waveform. The high duration of FI can be varied from 2 lines (minimum exposure) in multiples of 2 lines
up to 1306 lines (maximum exposure). The falling edge of FI is fixed within the frame, therefore it is the
leading edge of FI that must be moved to vary exposure.
The field read pulse, FR, must be set high for the 2 lines preceding the falling edge of FI; this means that the
FR waveform is identical to the FI waveform for minimum exposure. The necessary signal relationships are
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VISION VV6801/5801 PRELIMINARY CUSTOMER DATASHEET Rev 1.1
illustrated below:
LCK
EVEN
FI
FR
AVO
Exposure
Exposure
Exposure
1306 Lines (1 Frame)
Read Pixel Offsets
Valid Video Line
1306 Lines (1 Frame)
1306 Lines (1 Frame)
Live-Video Frames
Black Ref Line
y Figure 5.4 : Relative timing of Live Video mode
r If a frame buffer is being used to store the pixel to pixel DC offsets the first image captured on entering Live-
Video mode should have minimum exposure to obtain and store pixel offset data. However, if the offset data
a already exists in memory this step is not required.
in 5.4 Cine Modes
‘Cine’ mode is similar to ‘Live Video’ mode, since it continuously integrates and reads the array, but achieves
higher frame readout rates by subsampling the image both vertically and horizontally. Both Horizontal and
Vertical subsampling can be enabled in sensor timing.
lim 5.4.1 Horizontal Cine Mode
Selecting Horizontal Cine mode via the Serial Data Control Register (CR[2]) subsamples the pixels in a line,
reading out only every other pixel pair. (See Section 2.3 for details.) Horizontal Cine mode enables higher
e frame readout rates to be achieved, particularly when used in conjunction with Vertical Cine Mode.
For high frame readout rates, it is also best to read a dark frame into memory and subtract the Fixed Pattern
r Noise as the array is read in order to reduce the frame overhead of either line-rate CDS or the Shuttered
P Frame-rate cancellation schemes.
5.4.2 Vertical Cine Mode
This feature simplifies the timing requirements for vertical subsampling by removing the requirement to skip
lines through timing generation (which was necessary with the VV6850/5850). 3 hardwired subsampling
modes are available:
CR[18:17]
Vertical
Subsampling
Effect
Final viewfinder resolution
Max. frame
readout rate
@10MHz PCK
00
None
None
1280 x 1024 (Horizontal Cine 6.24/sec
Mode disabled)
01
1/2
Skip every 2nd
line pair
640 x 512 (With Horizontal
Cine Mode)
21/sec
10
1/4
Skip 3 line pairs in
every 4
320 x 256 (With Horizontal
Cine Mode and external pixel
subsampling)
42/sec
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