How to output to GUI window?

I am getting Voltage values from Arduino that I would like to display on a GUI window. All I am looking for is a window that displays "Voltage = whatever it is at that instance" Can't seem to figure it out. Any help is appreciated.

I have the following;

a=arduino();
interv=10000;
time=1;
t=0;
%
while (time<interv)
    time=time+1;
    Voltage=readVoltage(a,'A0');
    %     
    if Voltage > 1
        disp(Voltage);
    end
    drawnow
end

[Walter Roberson]

The disp() should work, provided that the Voltage is greater than 1. You will not need drawnow. And you are missing an 'end'

It might make more sense to use a "for" than a "while"

Answer 1

[OCDER]

Is this something you were aiming for? Not sure how your GUI is made, but here's a sample .m file you could start from.

 %myGUI.m
 function myGUI
      FH = figure('Visible', 'off');
      set(FH, 'unit', 'pixel', 'position', [100 100 140 100]);

      BTN = uicontrol(FH, 'Style', 'pushbutton', 'String', 'Read Voltage',...
          'Position', [20 20 100 20],...
          'Callback', @readVoltageInGUI);

      TXT = uicontrol(FH, 'Style', 'text', 'String', 'Voltage = []', ...
          'Position', [20 40 300 30], ...
          'HorizontalAlignment', 'left');

      set(FH, 'Visible', 'on')

      function readVoltageInGUI(SOURCE, EVENT)
          a = arduino(); 
          interv = 10000;
          time = 0;
          while (time<interv)
              time = time+1;
              Voltage = readVoltage(a, 'A0');
              if Voltage > 1
                  TXT.String = sprintf('Voltage (V) = %0.2f', Voltage);
                  drawnow
              end
          end
      end
 end

[Yigitcan Eron]

I think you get what I am trying to do. However, it's giving me the following error;

Error using myGUI/readVoltage Too many output arguments.

Error in myGUI/readVoltage (line 18) Voltage = readVoltage(a, 'A0');

Error while evaluating UIControl Callback.

[OCDER]

Oops, I accidentally overriden the readVoltage matlab function with the GUI's readVoltage function for updating the GUI. Look at the edited answer above. the "readVoltage" GUI function is renamed to "readVoltageInGUI".

[Yigitcan Eron]

Thank you! Now I am getting the following error:

Error using myGUI/readVoltageInGUI (line 13) MATLAB connection to Arduino Uno at COM3 exists in your workspace. To create a new connection, clear the existing object.

Error while evaluating UIControl Callback.

I managed to make it work once by working on your script but then I messed with it too much.

[OCDER]

https://www.mathworks.com/matlabcentral/answers/261075-how-can-i-run-matlab-connected-to-arduino-more-than-once

Issue is caused because you called a = arduino multiple time.

Something like this will prevent it from trying to make another arduino object.

if ~exist('a', 'var')
   a = arduino();  
end

Here are more help for clearing arduino connections.

https://www.mathworks.com/matlabcentral/answers/229868-how-do-i-close-the-port-arduino-is-connected-to