Generating a pulse width modulation (PWM)

Introduction

To dim a laser line generator, for example, you have to generate a pulse width modulation (PWM).

For this, you will need

• 2 timers and
• the active signal of the second timer at an output line

Using ImpactControlCenter

The following figures show, how you can set the timers using the GUI tool ImpactControlCenter

1. Setting of Timer1 (blue box) on the master camera:
   
   
   
   Figure 1: ImpactControlCenter - Setting of Timer1
   
2. Setting of Timer2 (purple on the master camera):
   
   
   
   Figure 2: ImpactControlCenter - Setting of Timer2
   
3. Assigning timer to DigOut (orange box in Figure 2).

Programming the pulse width modulation

You will need two timers and you have to set a trigger.

• Timer1 defines the interval between two triggers.
• Timer2 generates the trigger pulse at the end of Timer1.

The following sample shows a trigger

• which is generated every second and
• the pulse width is 10 ms:

#include <mvIMPACT_CPP/mvIMPACT_acquire.h>
#include <mvIMPACT_CPP/mvIMPACT_acquire_GenICam.h>

... 

// Master: Set timers to trig image: Start after queue is filled
    GenICam::CounterAndTimerControl catcMaster(pDev);
    catcMaster.timerSelector.writeS( "Timer1" );
    catcMaster.timerDelay.write( 0. );
    catcMaster.timerDuration.write( 1000000. );
    catcMaster.timerTriggerSource.writeS( "Timer1End" );

    catcMaster.timerSelector.writeS( "Timer2" );
    catcMaster.timerDelay.write( 0. );
    catcMaster.timerDuration.write( 10000. );
    catcMaster.timerTriggerSource.writeS( "Timer1End" );

See also

Counter And Timer Control

Note

Make sure the Timer1 interval must be larger than the processing time. Otherwise, the images are lost.

Now, the two timers will work like the following figure illustrates, which means

• Timer1 is the trigger event and
• Timer2 the trigger pulse width:

Figure 3: Timers

The timers are defined, now you have to set the digital output, e.g. "Line 0":

// Set Digital I/O
    GenICam::DigitalIOControl io(pDev);
    io.lineSelector.writeS( "Line0" );
    io.lineSource.writeS( "Timer2Active" );

See also

Digital I/O Control

This signal has to be connected with the digital inputs of the application.