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CV-A11
6.5. Edge Pre-select Mode
An external trigger pulse initiates the capture (input on pin 11 of the 12-pin Hirose connector or
pin 5 of the 6-pin Hirose). The leading edge of the trigger pulse initiates the exposure (this is a
falling edge if factory default). If the polarity of this pulse is reversed, the camera can be
configured to correct for it. The exposure time (accumulation time) is governed by the pre-
defined shutter speed set by RS-232C.
To use this mode:
Set function: Trigger mode “Edge Pre-select” TR=1
Shutter mode to “Normal” or “Programmable” SM=0, SM=1
Shutter Speed using fixed steps SH=0 through 7
or Programmable exposure PE=1 through 1023
Polarity and other functions
Input: Ext. trigger to pin 5 on 6 pin connector (or 11 on 12 pin connector)
Ext. HD to pin 6 on 12 pin connector. (If used).
Fig. 17. Edge pre-select
Important notes on using this mode:-
• As the start of exposure will be synchronized with the internal H signal, the start of
exposure may be shifted by max 1H. To avoid this shift (jitter), synchronize the camera
with an external HD and make sure that the trigger pulse aligns to the HD signal as shown
in Fig. 14.
• The duration of the external trigger pulse must be greater than 1H. It is recommended to
make this longer, typically 9H. This is a TTL level pulse, which can be positive or
negative going (the camera can be set to accept any polarity).
• Do not input ext. VD signal at pin 7 on 12 pin connector, as it may disturb the external
trigger function.
• Do not input a new trigger before the previous video is read out. (WEN is high).
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