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7.8
Controlling image capture
The camera supports the SHUTTER_MODES specified in IIDC v. 1.3. Each mode can be
combined with an external trigger. In this case individual images are recorded when an
external trigger impulse is present.
7.8.1
OneShot
The camera can record an image by setting “OneShot” in the 61Ch register. This bit is
automatically cleared after the image is captured. If the camera is placed in
Iso_Enable
mode (see
ISO_Enable
/ Free-Run), this flag is ignored.
If
OneShot mode
is combined with the external trigger, the “OneShot” command is used
to arm it. If the trigger impulse is absent being armed, OneShot can be cancelled by
clearing the bit.
7.8.2
Multi-Shot
Setting “MultiShot” and entering a quantity of images in
Count_Number
in the 61Ch
register enables the camera to record a specified number of images.
The number is indicated in bits 16 to 31. If the camera is put into
Iso_Enable
mode
(
ISO_Enable
/ Free-Run), this flag is ignored and is deleted automatically once all of
the images have been recorded.
If
MultiShot
mode is activated and the images are not yet finished being captured it can
be quit by resetting the flag. The same can be achieved by setting the number of
images to “0”.
7.8.3
ISO_Enable / Free-Run
Setting the “0” bit in the 614h register (ISO_ENA) puts the camera into
ISO_Enable
mode
or
Continuous_Shot
. The camera captures a series of images. This operation can be
quit by deleting the “0” bit.
7.8.4
Asynchronous broadcast
The camera accepts asynchronous broadcasts. This involves asynchronous write or read
requests that use node number 63 as the target node.
This makes it possible for all cameras on a bus to be triggered by software
simultaneously - e.g. by broadcasting a “One_Shot”. All cameras receive the “One_Shot”
command in the same cycle.
7.8.5
Jitter at start of exposure
Uncertainty over the actual start of exposure depends on the state of the camera. A
difference is made:
FVal is active
Æ
the sensor is reading out
FVal is inactive
Æ
the sensor is ready,
the camera is idle
If the sensor is ready a fixed time of 100 ns passes before the exposure begins. If the
sensor is reading out, the time until the exposure starts varies by the length of one
line.