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B
Camera Timing
B.1 Timed Exposure Mode Camera Timing
Fig. B.1 shows a timing example, when the camera capture frames with rising edges on the
camera ISO_IN input. The external signal, which is fed into the cameras ISO_IN input is isolated
by an opto-isolator. This signal is delayed by t
iso
−
in
before it reaches the FPGA input "Line In".
The "Line In" signal is synchronized to the FPGA clock domain and the rising edge is detected.
There is a clock uncertainty because of the synchronization logic which is shown by the
t
input
−
jitter
value. The input pulse can be delayed by the trigger delay feature (see Section 4.6.6)
according to the requirement of the application. Finally the exposure time cycle starts after an
offset delay t
exposure
−
offset
.
When the application needs a strobe pulse together with the image acquisition, the internal
line in pulse can also be used to start one of the timer. After the timer delay t
timer − delay
the
timer duration t
timer − duraton
is started which is shown by the timer active signal (see Section
5.2). The timer active signal needs to be selected to output it on "Line Out" (see Section 7.2),
which has a fix delay of t
lineout − offset
. The "Line Out" is isolated by an opto-isolator from the
camera electronics which leads to an additional delay of t
iso − out
.
The maximum exposure offset value t
exposure − offset
is up to the read out time of
one image row, when a new exposure starts during read out of the previous
image. In this case, the start of the exposure is postponed to the start of the
next image row read out.
Table B.1 gives an overview of the minimum and maximum values of the timing parameters.
Timing Parameter Min Value Max Value
t
iso
−
in
20 ns 165 ns
t
input − jitter
83.3 ns 111.1 ns
t
pulse
−
delay
0 s 0.466 s
t
exposure
−
offset
138.85 ns 138.85 ns
1)
/ (time of 2 image rows 23.5
µ
s)
2)
t
exposure
15.9
µ
s 0.466 s
t
timer
−
delay
0 s 119s
t
timer
−
duration
0 s 119 s
t
lineout − offset
111.1 ns 111.1 ns
t
iso − out
(ISO_OUT0 and ISO_OUT1) 150 ns 350 ns
t
iso
−
out
(ISO_OUT2) 15 ns 30 ns
Table B.1: GMAX4651 Camera timing parameter values of the timed exposure mode (Footnotes:
1)
New
exposure starts after readout of previous image;
2)
New exposure starts during readout of previous image)
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