15
15
3.3.2.4 Test Pattern Generator: (00 00 00 12)
A test pattern generator is built in. It is a useful tool to diagnose Ethernet communication and camera
functions. The output is 8-bit pattern.
3.3.3 Asynchronous Reset and No-delay Reset:
3.3.3.1 H and V Async Reset
The external trigger is a hardware trigger applied to pin #9 of GPIO connector with TTL level same as
Vinit or edge trigger. The default polarity is negative going edge. Positive going edge is selectable by
selecting the register (00 21 00 00 00 01).
GEViCAM has the no-delay reset capability to reset both horizontal and vertical without internal sync
delay. Only a few fixed pixel-clock delays (4 clocks typical) exist as the internal logic delay. The data
output delay occurs through the signal process but it is not the trigger or reset delay. The image cap-
ture is implemented with the internal no-delay reset timing thus they are always synchronized to the
trigger pulses regardless the number of cameras.
This eliminates a need of phase lock loop circuit for synchronizing multiple cameras.
3.3.3.2 Trigger Mode Selection (TriggerMode): (00 23)
In the trigger modes, there are various useful modes as follows;
(1) Async No-delay Trigger: (00 00 00 01)
It resets both internal H and V sync to pixel clock level.
The exposure time is programmable in each mode. The camera module outputs one FVAL equivalent
pulse per trigger for the image capturing. It finishes the complete frame before resetting with the next
trigger. If the trigger pulse comes in before the completion of frame data, it will be ignored. This fea-
ture avoids malfunction of image capturing caused by trigger noise and chattering.
(2) Pulse-width Control (ExposureWidth): (00 00 00 02)
It resets at both external pulse leading edge and trailing edge with no-delay reset. The exposure time
is exactly the same as the pulse width between the leading edge and the trailing edge.
(3) Hardware or Software Trigger (TriggerSelector)
The trigger type is selectable as a part of PLC (GPIO) functions. The hardware trigger is TTL external
trigger and the software trigger is initiated by the PLC program from the PC via Ethernet.
(4) Trigger Polarity (TriggerActivation): (00 21) (00 00 00 00, 01)
The leading edge polarity of either Falling edge or Rising edge is selectable (Factory Default: Falling
edge).
3.3.4 Exposure Control
3.3.4.1 Programmed Exposure Control: (00 24, 00 27, 00 28)
The programmed exposure control is done by electronic shutter mechanism which discharges the
photodiode electrons at the trigger and starts integrating at the shutter timing by counting number of H
clocks. Then the electronic charges are transferred to CCD shift registers to clocked out as video out-
put. This mechanism is applied to all async / shutter modes in normal scan mode, async mode, and
ITS mode. In essence, the electronic shutter control and exposure control is the same meaning.
Exposure
Control
(ExposureMode, ExposureTimeRaw):
(00 24
)
The exposure time is variable from 1n to FFFF (65535)n. “n” is number of counts of horizontal lines.
(n = 1H)
VGA
SXGA
XGA
1n = 19.5
µ
s
1n = 40.55
µ
s
1n = 40.64
(= 1/50,000sec)
(= 1/25,000sec)
(= 1/25,000 sec)
Example: n = FF in hex = 255 = 4.97 ms in VGA.
If you want to set 1ms (1/1000 s) for SXGA, n = 1000/40.55 = 25 = 19 (Hex).
So, enter “00 24 00 00 00 19”.
GEViCAM Inc
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