Have separate push button stop while loop executed by another push button

Hello,

I have a GUI that starts data collection through a while loop and I would like to have a push button that 'breaks.'

My Data collection push button is as follows:

if true
  function start_Callback(hObject, eventdata, handles)
handles.stop = 1;

    tic
    while toc<duration
        if handles.stop==0;
            break
        end
    tc = toc;
    %Tracker 0
    s1=analogin_mod(0,handles.phid);
    s1 = 100.*(s1-s1min)./(s1max-s1min);
    %(Insert Moving Average) s1v=[s1 s1v(1:2)];
    %Tracker 2
    s2=analogin_mod(1,handles.phid);
    s2 = 100.*(s2-s2min)./(s2max-s2min);
    %(Insert Moving Average)s2v=[s2 s2v(1:2)];
    %SineWave
    tNew=[tc-2:0.05:tc+3];
    yNew=interp1(handles.x,handles.y,tNew);
    plot(tNew,yNew,'-k','LineWidth',5);
    xlim([tc-2 tc+3]);
    ylim([-10 110]);
    hold on
    %Plot Trackers 
    plot(tc,s1,'-r.','MarkerSize',50);
    plot(tc,s2,'-b.','MarkerSize',30);
    drawnow;
    hold off;
    %CompileData
    tall(end+1)=toc;
    s1all(end+1)=s1;
    s2all(end+1)=s2;
    Track(end+1)=yNew(21);
    end
    data = [Track;tall;s1all;s2all]';
    assignin('base','data',data);
  end

I've tried to define 'stop' and then in the while loop have an 'if' statement that will break the loop if stop changes values.

my second push button is as follows:

if true
  function stop_Callback(hObject, eventdata, handles)
  handles.stop =0;
end

My hope is that if I push the 'Stop' button then stop will change in the first button to == 0 and therefore the while loop will break.

Can anyone help? Also, is there a better/easier way of achieving this effect?

Thanks