How to make a MATLAB function wait until a timer stops running

Question

I have a function func1 that calls another function func2, which, in turn, starts a timer object. I need func1 to pause until the timer stops. How can I do this?

The timer is not a SingleShot Timer but a Periodic Timer stopped using stop() on a condition tested in its TimerFcn.

The timer doesn not stop when it calls @timerCallback but only after it finished calling the callback (as many times as you define, but y default just once). — Oleg
– Oleg, Commented Aug 21, 2013 at 14:34
Yes, you are right, the timer stops when it finished calling the callback, but still I have the problem — Bedo
– Bedo, Commented Aug 21, 2013 at 14:54

Eitan T · Accepted Answer · 2013-08-21 14:42:50Z

3

Use wait() to halt execution until the timer stops:

function func1
    thandle = func2;
    wait(thandle)
    disp(1)
end

function h = func2
    h = timer('StartFcn',@(ev,obj)fprintf('Started timer'),'TimerFcn',@(ev,obj)pause(2));
    start(h)
end

Note that func2() is a subfunction of func1() but can also be an external function, the only requirement is that it returns the handle to the timer object.

Try the example by simply calling foo in the command window.

edited Aug 21, 2013 at 14:42

Eitan T

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answered Aug 21, 2013 at 14:31

Oleg

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5 Comments

Bedo Over a year ago

This solution does not work because my timer has an infinite number of tasks to execute and it is stopped using "stop()". I get this error: "Can't wait with a timer that has an infinite TasksToExecute." function th = subfoo global h; %h = timer('StartFcn',@(ev,obj)fprintf('Started timer'),'TimerFcn',@(ev,obj)pause(5)); th = timer('Name', 'Refresher', 'TimerFcn',@refresherCallback,'ExecutionMode','fixedRate','Period', 0.5); h = th; start(th) end function refresherCallback(~,~) global h; counter = get(h, 'TasksExecuted'); if ( counter > 10) stop(h); end end

Oleg Over a year ago

@Bedo Elaborate your orginal question to give more context to what you are trying to accomplish. Otherwise it's impossible to provide a working solution to a generic question.

Bedo Over a year ago

Yes, sorry. The original question contains all detail needed. I have just added the fact that the timer is not a SingleShot but a Periodic timer stopped on a condition tested in its TimerFcn.

Bedo Over a year ago

At the end I decided to start from this solution and to add a new SingleShot timer with a very high start delay that stops when my periodic timer stops. It works! Thank you

Oleg Over a year ago

What I was asking to give you better directions is the general workflow that you want oto achieve. I suspect that what you're trying to accomplish can be done in a simpler way. Feel free to update your question or ask another one if you encounter problems with the complexity of the overall structure

Nick · Accepted Answer · 2013-08-21 14:23:49Z

2

You can return the timer object to func1 and implement a wait loop there:

while strcmp(to.Running, 'on')
    % Do Nothing
end

answered Aug 21, 2013 at 14:23

Nick

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4 Comments

Bedo Over a year ago

Will this work if func1 and func2 are on two different .m files? And is this a busy waiting? Busy waiting is not acceptable for me...

Nick Over a year ago

No it will wait until the timer has stopped running, either as it is being stopped or it has finished its execution command.

Bedo Over a year ago

I tried and it works but the while cycle is a busy waiting and Matlab uses 100% of my CPU for nothing (and for a lot of time). This is not a good idea :(

Bedo Over a year ago

I added a pause(2) inside the while and now it works better since I don't need real time execution. Still I think this is a work around...

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