MATLAB: Break a while loop in a GUI Pushbutton

assigninguiinterruptpushbuttonwhilewhile interrupt

Hi there,
I have a GUI set up and it has a Start pushbutton and a Stop pushbutton. Upon pushing the start, data is transmitted and received between AVR and matlab with Serial communication.
What I am trying to do is while the data is communicated and being run, if the stop button is pressed, the while operation should stop. This should be accomplished if I can just break the while loop, but the code that I've tried using 'assignin' and 'evalin' hasn't succeeded. Actually it occasionally works but sometimes doesn't work. Here is what my code :
function StartButton_Callback(hObject, eventdata, handles)
flag = 0;
assignin('base','flag', flag);
bt = Bluetooth('JCNET-BT-7827',1);
fopen(bt);
while 1
    %%Receiving and Display Serial Communication
    flag = evalin('base', 'flag');
    if flag == 1
        break;
    end
end
When the EndButton is pressed,
% --- Executes on button press in EndButton.
function EndButton_Callback(hObject, eventdata, handles)
flag = 1;
assignin('base','flag', flag);
Could anyone give me for advices? Thanks a lot in advance!

Best Answer

Hi MINKYUNG KIM,
below you find an example for breaking a while loop within a pushbutton controlled GUI. The data exchange is done using guidata. Avoid assignin and evalin if possible. These methods are silly to debug and prone to errors.
function GuiBreak
    GUI.fh = figure;
    
    GUI.h1 = uicontrol('style','Edit',...
                   'string','XX',...
                   'Units','normalized',...
                   'Position',[0.1 0.1 0.8 0.2],...
                   'backgroundcolor','c',...
                   'Tag','EditField2',...
                   'Enable','off');
    
    GUI.h2 = uicontrol('Style','PushButton',...
                   'String','Start',...
                   'Units','normalized',...
                   'Position',[0.1 0.4 0.3 0.2],...
                   'callback',{@func_compute},...
                   'Tag','StartButton',...
                   'backgroundcolor',...
                   'g','FontSize',12);
                   
    GUI.h3 = uicontrol('Style','PushButton',...
                   'String','Stop',...
                   'Units','normalized',...
                   'Position',[0.5 0.4 0.3 0.2],...
                   'callback',{@breakOP},...
                   'Tag','StopButton',...
                   'backgroundcolor',...
                   'r','FontSize',12);
    
    myHandle = guihandles(GUI.fh);  % save gui handles to struct
    myHandle.breakOP = false;       % flag for break OP
    guidata(GUI.fh,myHandle);       % save structure

end
function func_compute(~,~)
    
    a = 1;
    while 1
        myHandle = guidata(gcbo);                   % get structure

        myHandle.EditField2.String = num2str(a);    % edit field string
        pause(0.01);
        if myHandle.breakOP                         % check for break OP flag
            break;
        end
        a = a +1;
    end
   
end
function breakOP(~,~)
    myHandle = guidata(gcbo);   % get structure
    myHandle.breakOP = true;    % change break OP flag
    guidata(gcbo,myHandle);     % save structure
end
Kind regards,
Robert
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