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Editorial Team
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Asked: 2026-06-17T20:07:03+00:00

EDIT: I rephrased my question a bit, because I have a better understanding of

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EDIT: I rephrased my question a bit, because I have a better understanding of the problem now and there was a lot of unnecessary info in the first draft.

I am creating a standalone MATLAB application, which needs a toggle button that can initiate and stop a looping script.

Based on this helpful video, I was able to implement this idea like this in my gui.m file:

function startBtn_Callback(hObject, eventdata, handles)

    if get(handles.startBtn,'Value')
        set(handles.startBtn,'String','Stop Recording');
    else
        set(handles.startBtn,'String','Start Recording');
    end

    while get(handles.startBtn,'Value');
        disp('looping..');
        pause(.5);
    end

This script works as expected, but when I replace the contents of the while loop the function I would like to loop, the button stops working. It still toggles when I push it, but the callback only gets called the first time the button is pushed. Here is what my final code looks like:

function startBtn_Callback(hObject, eventdata, handles)

    if get(handles.startBtn,'Value')
        set(handles.startBtn,'String','Stop Recording');
        pause(.1);
    else
        set(handles.startBtn,'String','Start Recording');
        disp('Recording Stopped')
    end

    while get(handles.startBtn,'Value');
        myFunction();
    end

When I push the start button, this callback runs and the loop starts. The pause(.1) is needed to get the text to change – if I don’t include a pause, the loop initiates, but the text on the button does not change.

After this, no subsequent button pushes do anything. The button toggles on the GUI, but startBtn_Callback never gets called and the loop runs indefinitely. This is a problem because my end user will not have access to the MATLAB console.

To give a bit more information about my function: its a method that records audio for 5 seconds, does some processing, then outputs some graphs. I want this loop to repeat indefinitely until the user pushes stop.

I think that the issue is that MATLAB seems to only be able to run one function at a time, so when myFunction() is running, the callback can’t be initiated. The reason it worked in the first example is because there was a pause between loop calls. I can’t have this pause, because a requirement of the project is to record every possible second.

How can I make a reliable stop button for this process?

I am running MATLAB R2012b 32-bit.

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1 Answer

  1. Editorial Team

    drawnow() is the function I was looking for. Putting that after myFunction() forces Matlab to handle any stacked up GUI calls before proceeding with the loop.

    This code creates a reliable start/stop toggle button for an indefinite and continuous process:

    function startBtn_Callback(hObject, eventdata, handles)

  if get(handles.startBtn,'Value')
      set(handles.startBtn,'String','Stop');
      drawnow();
  else
      set(handles.startBtn,'String','Start');
  end
  while get(handles.startBtn,'Value');
      myFunction();
      drawnow()
  end
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