MATLAB: Using callback function in timer with a function generated within script

Question

Hi all,

I think I have a reasonably straightforward question. I am trying to use a timer function in matlab but I am getting a consistent error. I have generated a gui and I want it to execute a function periodically when a button is pressed. The troublesome part of the code looks like this

acquisitionTimer = timer;
acquisitionTimer.ExecutionMode = 'fixedRate';
acquisitionTimer.TasksToExecute = sweepsPerTrigger;
acquisitionTimer.Period = inter_stimulus_interval;
acquisitionTimer.StopFcn = @acquisitionTimerCleanup;
acquisitionTimer.TimerFcn = @(myTimerObj, thisEvent)startAcquisition;
start(acquisitionTimer);
function acquisitionTimerCleanup(acquisitionTimer,~)
disp('Done Acquiring');
delete(acquisitionTimer)
function startAcquisition
(this starts my aquisition code)

— So I think my problem is with the callback function line

acquisitionTimer.TimerFcn = @(myTimerObj, thisEvent)startAcquisition;

I get the impression this is not how you start a function when linking it with a timer. Any advice would be greatly appreciated. I looked at the documention, but unfortunately, I can't seem to figure it out right now.

Thanks, Quentin

Answer 1

I put your code into one m-file and it worked. I cannot see any problem. With R2013a

    >> cssm
    start Acquisition
    start Acquisition
    Done Acquiring
    >>

where cssm is

    function cssm
        acquisitionTimer = timer;
        acquisitionTimer.ExecutionMode = 'fixedRate';
        acquisitionTimer.TasksToExecute = 2;
        acquisitionTimer.Period = 1;
        acquisitionTimer.StopFcn = @acquisitionTimerCleanup;
        acquisitionTimer.TimerFcn = @(myTimerObj, thisEvent)startAcquisition;
        start(acquisitionTimer);
    end
    function acquisitionTimerCleanup(acquisitionTimer,~)
        disp('Done Acquiring');
        delete(acquisitionTimer)
    end
    function startAcquisition
    %    (this starts my aquisition code)
        disp('start Acquisition')
    end