Making STOP - Button

Hi everybody! I'm new here and have a question about GUI's.

I have a GUI which contains (among other things) two (push)buttons. The first one is a "Start" button and the second one should be some kind of a "Stop" button. By pressing "Start" an infinite loop begins and the program starts reading a certain amount of data from a port and saves it to a file. When it finished reading it waits a few seconds and starts reading again. This happens x times, where x is a predifined value.

Now I want, that pressing the "Stop"-Button forces the program to stop at n < x runs (n depending on when I press the button).

For that purpose I defined a variable "run", which is 1 and gets 0, when "Stop" is pressed. So an exit is possible.

That's the plan. Unfortunatelly that doesn't work. I assume, that the rest of the GUI is "frozen" while the program is stuck in the loop, so pressing "Stop" doesn't change anything. I supposed pressing the button triggers some kind of interrupt, so being stuck in the loop is no problem, but sadly it seems as I am wrong (or I have to enable the interrupt, without knowing how). I already read a related post, where the questioner was advised to use a checkbox instead, but sadly this is no option for my purpose.

I hope some of you can help me? :)

Thank you!

[Antonio De lavalle]

excuse a doubt I need to make a music note player but they also ask me to incorporate a pause button in the program

Answer 1

[Dennis]

It is hard to guess why it doesn't work without seeing any actual code. Your GUI is not frozen while your loop is running.

Small working exampel:

handles.fig=figure;
handles.pb1=uicontrol('style','pushbutton','position',[100 100 80 40],'callback',@start_cb,'string','Start');
handles.pb2=uicontrol('style','pushbutton','position',[200 100 80 40],'callback',@stop_cb,'string','Stop');
handles.run=1;
guidata(handles.fig,handles)
function start_cb(hObj,~)
while true
    handles=guidata(hObj);
    if handles.run==1
    disp('running')
    pause(1)
    else
        handles.run=1;
        guidata(hObj,handles)
        disp('stopped')
        break
    end
end
end

function stop_cb(hObj,~)
handles.run=0;
guidata(hObj,handles)
end

[noNickame]

Hi - thanks for your respond!

Sorry for posting no code - I was pretty sure, that this "frozen in loop" is the problem, so I thought, that it makes no sense to post code.

Your code-example works fine, if I paste it into a new file, but I still have some problems using it in my code (Du to it's my first time with GUIs I used GUIDE to create my GUI, so it looks a little bit different.)

In detail I don't know what this "handles.run" is and where to create it (and Matlab seems like it doesn't know either). I tried to avoid handles.run via using a global variable, so it works, but I guess this is not very smart or stylisch.

Now the code (with handels.run, which doesn't work)

 function varargout = TestGUI(varargin)
% Begin initialization code - DO NOT EDIT
gui_Singleton = 1;
gui_State = struct('gui_Name',       mfilename, ...
                   'gui_Singleton',  gui_Singleton, ...
                   'gui_OpeningFcn', @TestGUI_OpeningFcn, ...
                   'gui_OutputFcn',  @TestGUI_OutputFcn, ...
                   'gui_LayoutFcn',  [] , ...
                   'gui_Callback',   []);
 if nargin && ischar(varargin{1})
    gui_State.gui_Callback = str2func(varargin{1});
 end

     if nargout
        [varargout{1:nargout}] = gui_mainfcn(gui_State, varargin{:});
      else
      gui_mainfcn(gui_State, varargin{:});
      end
     % End initialization code - DO NOT EDIT
  end
function TestGUI_OpeningFcn(hObject, eventdata, handles, varargin)
handles.output = hObject;
guidata(hObject, handles);
axes(handles.Diagramm2);
cla;
function StartButton_Callback(hObject, eventdata, handles)
 if ~isempty(instrfind)
           fclose(instrfind)
       end

 while(true)
 handles=guidata(hObject);
      if handles.run==1
        %Code
      end
      else
            handles.run=1;
            guidata(hObj,handles)
            disp('stopped')
            break

      end
function StoppButton_Callback(hObject, eventdata, handles)
handles.run=0;
guidata(hObject,handles)

[Dennis]

You can place handles.run in your opening function to pass it along with your other handles.

 function varargout = TestGUI(varargin)
% Begin initialization code - DO NOT EDIT
gui_Singleton = 1;
gui_State = struct('gui_Name',       mfilename, ...
                   'gui_Singleton',  gui_Singleton, ...
                   'gui_OpeningFcn', @TestGUI_OpeningFcn, ...
                   'gui_OutputFcn',  @TestGUI_OutputFcn, ...
                   'gui_LayoutFcn',  [] , ...
                   'gui_Callback',   []);
 if nargin && ischar(varargin{1})
    gui_State.gui_Callback = str2func(varargin{1});
 end

     if nargout
        [varargout{1:nargout}] = gui_mainfcn(gui_State, varargin{:});
      else
      gui_mainfcn(gui_State, varargin{:});
      end
     % End initialization code - DO NOT EDIT
  end
function TestGUI_OpeningFcn(hObject, eventdata, handles, varargin)
handles.output = hObject;

handles.run=1;  % this is new

guidata(hObject, handles);

axes(handles.Diagramm2);
cla;
function StartButton_Callback(hObject, eventdata, handles)
 if ~isempty(instrfind)
           fclose(instrfind)
       end

   while(true)
   handles=guidata(hObject);
        if handles.run==1
          %Code
        end
        else
              handles.run=1;
              guidata(hObj,handles)
              disp('stopped')
              break

        end
  function StoppButton_Callback(hObject, eventdata, handles)
  handles.run=0;
  guidata(hObject,handles)

[Tayyaba Abro]

Hello Dennis, can you please help me to implement your code. Actually I am sending continuous data from realterm to MATLAB. I want MATLAB to stop taking data on pressing "Stop button". After stopping data it should ask to input specific row number. And in last it should display that specific row in the text box. Your code worded perfectly in separate .m file but it is not working in my code as it do not stop taking data. Here is my demo code:

function varargout = showguide(varargin)
% SHOWGUIDE MATLAB code for showguide.fig
%      SHOWGUIDE, by itself, creates a new SHOWGUIDE or raises the existing
%      singleton*.
%
%      H = SHOWGUIDE returns the handle to a new SHOWGUIDE or the handle to
%      the existing singleton*.
%
%      SHOWGUIDE('CALLBACK',hObject,eventData,handles,...) calls the local
%      function named CALLBACK in SHOWGUIDE.M with the given input arguments.
%
%      SHOWGUIDE('Property','Value',...) creates a new SHOWGUIDE or raises the
%      existing singleton*.  Starting from the left, property value pairs are
%      applied to the GUI before showguide_OpeningFcn gets called.  An
%      unrecognized property name or invalid value makes property application
%      stop.  All inputs are passed to showguide_OpeningFcn via varargin.
%
%      *See GUI Options on GUIDE's Tools menu.  Choose "GUI allows only one
%      instance to run (singleton)".
%
% See also: GUIDE, GUIDATA, GUIHANDLES

% Edit the above text to modify the response to help showguide

% Last Modified by GUIDE v2.5 04-Mar-2023 18:02:01

% Begin initialization code - DO NOT EDIT
gui_Singleton = 1;
gui_State = struct('gui_Name',       mfilename, ...
                   'gui_Singleton',  gui_Singleton, ...
                   'gui_OpeningFcn', @showguide_OpeningFcn, ...
                   'gui_OutputFcn',  @showguide_OutputFcn, ...
                   'gui_LayoutFcn',  [] , ...
                   'gui_Callback',   []);
if nargin && ischar(varargin{1})
    gui_State.gui_Callback = str2func(varargin{1});
end

if nargout
    [varargout{1:nargout}] = gui_mainfcn(gui_State, varargin{:});
else
    gui_mainfcn(gui_State, varargin{:});
end
% End initialization code - DO NOT EDIT


% --- Executes just before showguide is made visible.
function showguide_OpeningFcn(hObject, eventdata, handles, varargin)
% This function has no output args, see OutputFcn.
% hObject    handle to figure
% eventdata  reserved - to be defined in a future version of MATLAB
% handles    structure with handles and user data (see GUIDATA)
% varargin   command line arguments to showguide (see VARARGIN)

% Choose default command line output for showguide
handles.output = hObject;

handles.run=1

% Update handles structure
guidata(hObject, handles);

% UIWAIT makes showguide wait for user response (see UIRESUME)
% uiwait(handles.figure1);


% --- Outputs from this function are returned to the command line.
function varargout = showguide_OutputFcn(hObject, eventdata, handles) 
% varargout  cell array for returning output args (see VARARGOUT);
% hObject    handle to figure
% eventdata  reserved - to be defined in a future version of MATLAB
% handles    structure with handles and user data (see GUIDATA)

% Get default command line output from handles structure
varargout{1} = handles.output;


% --- Executes on button press in pushbutton1.
function pushbutton1_Callback(hObject, eventdata, handles)
% hObject    handle to pushbutton1 (see GCBO)
% eventdata  reserved - to be defined in a future version of MATLAB
% handles    structure with handles and user data (see GUIDATA)

realterm = actxserver ('realterm.realtermintf')
realterm.port = '5'
realterm.portopen=1
s = serial('COM4', 'Baudrate', 57600)
fclose(s)
fopen(s)
serial_baudrate = s.baudrate
data = '' 
pause (15)
while (1) 
  handles=guidata(hObject);
  if handles.run==1
    new_data = fscanf(s) 
    data = [data, new_data] 
    realterm_baudrate = realterm.baud
    set(handles.text3, 'String', num2str(realterm_baudrate))
    serial_baudrate = realterm_baudrate
    set(handles.text4, 'String', num2str(serial_baudrate))
    arrange_data = textscan(data,'%s','Delimiter',' ') %arrange data in array 
    extract_data = arrange_data{:}  % shows arranged data scanned by textscan
    set(handles.text2, 'String', extract_data)
    else
              handles.run=1;
              disp('stopped')
              row_data = extract_data(3,:)
              set(handles.text5, 'String',row_data)
              break
        end
end 


% --- Executes on button press in pushbutton2.
function pushbutton2_Callback(hObject, eventdata, handles)
% hObject    handle to pushbutton2 (see GCBO)
% eventdata  reserved - to be defined in a future version of MATLAB
% handles    structure with handles and user data (see GUIDATA)
handles.run=0;
  guidata(hObject,handles)

Answer 2

[Rik]

I use a uicontrol togglebutton in such cases:

%in your looping code:
if get(handles.togglebutton,'Value')
    break
end

%in the callback of the button:
set(hObject,'Value',1)

[noNickame]

Hi! Thanks for your answer!

I already considered using a toggle-button, but the problem is, that - as a toggle-button should do - the button stays "out". So when I start next time it still ends after one run. This is fine for me, who knows, that I need to reset the button, but it might be a problem for an end-user.

So toggle-buttons don't seem to fit for 100%.

Maybe I understood your suggestion wrong and you meant, that I can use one toggle-button instead of two push-buttons? If yes this should be working fine!

[Rik]

You indeed need to reset the togglebutton value when you start your code. You could use a normal pushbutton instead, but that means that you need to be very careful where you load and reload your guidata.

So at the start of you looping function (before you enter the loop), you'll need to set(handles.togglebutton,'Value',1), and then it should work.

PS you see why I don't use GUIDE: a forest of functions calling each other in a convoluted way. Really difficult to understand where you should make changes.