MATLAB IMAGE ACQUISITION TOOLBOX 3 Guida Utente Scaricare il pdf (Pagina 202)

100

101

7 Using Events and Callbacks

function mem_mon(o bj,e vent)

out = imaqmem;

mem_left = out.FrameMe moryLimit - out.FrameMe moryUsed;

msg = 'Memory left for frames ';

msg2 = 'Memory load';

low_limit = 2000000;

if(mem_left > low_limi t)

sprintf('%s: %d \n%s: %d',msg, mem_left,msg2, out.MemoryLoa d)

else

disp('Memory avail abl e fo r frames getting low.');

disp('Stopping acq uis ition.')

stop(obj);

end

Running the Example

The example acquires frames until the amount of memory left for frame

storage reaches a lower limit specified in the callback function.

1 Create an im age acquisition object — Th i s example creates a video

input o bj ect for a M atrox ima ge acquisition device. To run th is example on

your system, use the

imaqhwinfo function to get the object constructor for

your image acquisition device and substitute that syntax for the following

code.

vid = videoinput('mat rox',1);

2 Configure property values — This example sets up a continuous

acquisition by setting the

FramesPerTrigger value to Inf.Theexample

also spe c ifies the timer e vent call back function

mem_mon, created in

“Creating the Memory Monitor Callback Function” on page 7-17, as the

value of the

TimerFcn callback. The object will execute the TimerFcn every

five seconds, as specified by the valu e of the

TimerPeriod property.

set(vid,'FramesPerTrigger',Inf);

set(vid,'TimerPeriod',5);

set(vid,'TimerFcn',{'mem_mon'});

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MATLAB IMAGE ACQUISITION TOOLBOX 3 Guida Utente Pagina 202

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