Point Grey Flea3 USB 3.0 Technical Reference 4 Input/Output Control
4.2.3 GPIO Mode 2: Asynchronous (External) Trigger
When a GPIO pin is put into GPIO Mode 2, and an external trigger mode is enabled (which disables isochronous data
transmission), the camera can be asynchronously triggered to grab an image by sending a voltage transition to the pin.
See Asynchronous Triggering on page 81.
4.2.4 GPIO Mode 3: Strobe
A GPIO pin in GPIO Mode 3 will output a voltage pulse of fixed delay, either relative to the start of integration (default)
or relative to the time of an asynchronous trigger. A GPIOpin in this mode can be configured to output a variable
strobe pattern. See Programmable Strobe Output below.
4.2.5 GPIOMode 4: Pulse Width Modulation (PWM)
When a GPIO pin is set to GPIO Mode 4, the pin will output a specified number of pulses with programmable high and
low duration. See Pulse Width Modulation (PWM) on page 50.
4.3 Programmable Strobe Output
The camera is capable of outputting a strobe pulse off select GPIO pins that are configured as outputs. The start of the
strobe can be offset from either the start of exposure (free-running mode) or time of incoming trigger (external
trigger mode). By default, a pin that is configured as a strobe output will output a pulse each time the camera begins
integration of an image.
The duration of the strobe can also be controlled. Setting a strobe duration value of zero produces a strobe pulse with
duration equal to the exposure (shutter) time.
Multiple GPIO pins, configured as outputs, can strobe simultaneously.
Connecting two strobe pins directly together is not supported. Instead, place a diode on each strobe pin.
The camera can also be configured to output a variable strobe pulse pattern. The strobe pattern functionality allows
users to define the frames for which the camera will output a strobe. For example, this is useful in situations where a
strobe should only fire:
n Every Nth frame (e.g. odd frames from one camera and even frames from another); or
n N frames in a row out of T (e.g. the last 3 frames in a set of 6); or
n Specific frames within a defined period (e.g. frames 1, 5 and 7 in a set of 8)
Title Article
Buffering a GPIO pin strobe output signal using an optocoupler to drive external devices
Knowledge Base Article 200
GPIO strobe signal continues after isochronous image transfer stops
Knowledge Base Article 212
Setting a GPIOpin to output a strobe signal pulse pattern
Knowledge Base Article 207
Related Knowledge Base Articles
Revised 9/27/2012
Copyright ©2011-2012 Point Grey Research Inc.
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