Strobe control from a camera
The BU and BG series, the BC series models with an I/O connector, and the DU, DDU, and EX series (hereinafter collectively referred to as the B/D/E series) provide a high-performance general-purpose input/output (GPIO).
Combining the functions of the GPIO makes it possible to control the strobe light timing from a camera.
As an example, the following shows the configuration of the GPIO of the BU series:
Either an output pin (Line1 in the case of the BU series) or an I/O pin (Line2 in the case of the BU series) can be used for strobe control. To use an I/O pin, it is necessary to set the relevant bit of LineModeAll to the output mode.
// Setting Line2 to the output mode
SetCamLineMode(s_hCam, CAM_LINE_SELECTOR_LINE2, CAM_LINE_MODE_OUTPUT );
The input polarity depends on the strobe connected.
In the case of the B/D/E series, the factory default of the GPIO output polarity is negative. To use a strobe with an input pulse of positive polarity, the LineInverterAll register should be programmed to reverse the camera’s polarity.
The following shows an example of a strobe connection.
// Inverting the output signal of Line2 to set the polarity to positive
SetCamLineInverter(s_hCam, CAM_LINE_SELECTOR_LINE2, true );
3.Methods of setting the strobe output signal
When a camera and a strobe are connected in a typical manner, this method is used to fire the strobe during the camera's exposure.
Use this method for TriggerMode = Off, TriggerSequence1 (Level mode) and TriggerSequence6 (Bulk mode).
// Configuring the output signal of Line2 for ExposureActive
SetCamLineSource (s_hCam, CAM_LINE_SELECTOR_LINE2, CAM_LINE_SOURCE_EXPOSURE_ACTIVE);
In some cases, the strobe flash and discharge delays can be an issue when the exposure time is short. In such cases, it is effective to set the expose time to a period during which the strobe brightness level is stable.
The B/D/E series provides a Pulse generator called TimerControl. This function makes it possible to set strobe flash and camera exposure parameters arbitrarily.
This method is available only TriggerSequence0 (Edge mode).
*BG Series (CCD) and BG205M-CS don’t have this function.
// Example of setting an exposure of 500 μs at the center of the strobe flash time of 700 μs
// Configuring the reference signal for the Timer0Active signal to accept a trigger
SetCamTimerTriggerSource(s_hCam, CAM_TIMER_TRIGGER_SOURCE_FRAME_TRIGGER );
// Setting a delay of the Timer0Active signal (zero delay)
SetCamTimerDelay( s_hCam, 0 );
// Setting the width of the Timer0Active signal to 700 μs
SetCamTimerDuration( s_hCam, 700 );
// Configuring the output signal of Line2 for Timer0Active
SetCamLineSource (s_hCam, CAM_LINE_SELECTOR_LINE2, CAM_LINE_SOURCE_TIMER0_ACTIIVE );
// Setting the latency between the detection of a trigger signal and the beginning of exposure to 100 μs
SetCamTriggerDelay( s_hCam,100 );
// Setting the exposure time to 500 μs
SetCamExposureTime( s_hCam, 500 );