ACS-I1024-CPGA Photon Vision Systems, Inc., ACS-I1024-CPGA Datasheet - Page 16

• Manufacturer Part Number: ACS-I1024-CPGA
• Description: High Performance Area CMOS Image Sensor
• Manufacturer: Photon Vision Systems, Inc.

MODES OF OPERATION
FULL FRAME SNAPSHOT SHUTTER – DESTRUCTIVE READOUT
This mode captures an image by simultaneously integrating all pixels. After integration, all pixels are simultaneously
transferred to the hold site. This cycle begins when SYNC line is asserted after the !STOP bit is released in
synchronous mode, or immediately after the !STOP bit is released in asynchronous mode. The FFS HOLDOFF register
and TRANSFER register count down and all pixels are held in reset until the FFS HOLDOFF register reaches zero, and
then the pixels begin to integrate. Once the TRANSFER register reaches zero, all pixels are transferred to the hold site.
Therefore the integration time is the difference between the FFS HOLDOFF and the TRANSFER registers in exposure
clock periods as defined by CS0. The array is then read out progressively. If !STOP equals one, another cycle will
begin. Otherwise, the device will halt until !STOP becomes one.
FULL FRAME SNAPSHOT SHUTTER – NON-DESTRUCTIVE READOUT
This mode operates in similar fashion to FFS mode described above, except that the pixels are read non-destructively.
The cycle begins in the same manner as Full Frame Destructive, and pixels are sampled when the TRANSFER register
reaches zero. All pixels are read out non-destructively, and therefore the CDS is disabled. Another cycle begins after
the transfer register is reloaded if !STOP is one. If !STOP is not one, the machine will go halt when read out is
completed.
ROLLING SHUTTER – DESTRUCTIVE READOUT
A cycle begins the same way as Full Frame Destructive, although this method samples one row at a time. Each row is
read the same as Full Frame Destructive, but it is reset and unless a ROLLING HOLDOFF is set, begins integrating
immediately after the reading. The rolling holdoff register can be used to prevent the image from becoming over-
exposed. A row will not begin integrating again until an additional number of lines equal to the rolling holdoff register
are read. As with the other modes, another cycle begins when !stop is one, and the machine goes idle when !stop is
zero. If multiple regions of interest with a different number of pixels per row are used, the exposure for different ROIs
will not be equal because of different line times for the multiple ROIs. The following equations can be used:
Exposure time = (number of lines – rolling holdoff)(line time)
Line time = (2 uSEC) + (pixels per line)(50 nSEC)
Product DATASHEET ACS-I XXX Rev. 10/31/00 Subject to change without notice. Page 16 of 26
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Photon Vision Systems, Inc. 1999, 2000
PRELIMINARY