How do I utilize a timer in the App Designer to capture serial data?

Hey all,

I'm trying to capture serial data from an app programmed in the app designer but am having trouble with the timer object. I have a snippet of code below as a simple example that has an text box for displaying an increment value and the timer status.

I have a callback function which executes to increment the value of the text box each 0.1 s. But when I run the program, or click the button to start the timer, the timer object does not start. Can anyone help me out?

classdef App4 < matlab.apps.AppBase

      % Properties that correspond to app components
      properties (Access = public)
          UIFigure         matlab.ui.Figure
          EditFieldLabel   matlab.ui.control.Label
          EditField        matlab.ui.control.NumericEditField
          EditField2Label  matlab.ui.control.Label
          EditField2       matlab.ui.control.EditField
          Button           matlab.ui.control.Button
      end

      properties (Access = private)
          tickr = 69; % Description

      end

      properties (Access = public)
          timr;
      end

      methods (Access = private)

      end

      methods (Access = public)

          function incrimentTick(app)

              app.EditField.Value = app.tickr;
          end

                 function incrimentTick2(app)
              app.tickr = app.tickr + 1;
              app.EditField.Value = app.tickr;
          end

      end

      methods (Access = private)

          % Code that executes after component creation
          function startupFcn(app)

              app.timr = timer('StartDelay', 0, 'Period', 0.5,'ExecutionMode', 'fixedRate');
              app.timr.TimerFcn = @(obj,event)incrementTick(app);

                  start(app.timr);

                  start(app.timr);

                  if (strcmp(app.timr.Running,'on') == 1)
                    app.EditField2.Value = 'on';  
                  end

                  if (strcmp(app.timr.Running,'off') == 1)
                    app.EditField2.Value = 'off';  
                  end
          end

          % Button pushed function: Button
          function ButtonPushed(app, event)
              start(app.timr);

                  if (strcmp(app.timr.Running,'on') == 1)
                    app.EditField2.Value = 'on';  
                  end

                  if (strcmp(app.timr.Running,'off') == 1)
                    app.EditField2.Value = 'retry';  
                  end
          end
      end

      % App initialization and construction
      methods (Access = private)

          % Create UIFigure and components
          function createComponents(app)

              % Create UIFigure
              app.UIFigure = uifigure;
              app.UIFigure.Position = [100 100 640 480];
              app.UIFigure.Name = 'UI Figure';
              setAutoResize(app, app.UIFigure, true)

              % Create EditFieldLabel
              app.EditFieldLabel = uilabel(app.UIFigure);
              app.EditFieldLabel.HorizontalAlignment = 'right';
              app.EditFieldLabel.Position = [231.03125 233 56 15];
              app.EditFieldLabel.Text = 'Edit Field';

              % Create EditField
              app.EditField = uieditfield(app.UIFigure, 'numeric');
              app.EditField.Position = [302.03125 229 100 22];

              % Create EditField2Label
              app.EditField2Label = uilabel(app.UIFigure);
              app.EditField2Label.HorizontalAlignment = 'right';
              app.EditField2Label.Position = [228.703125 159 62 15];
              app.EditField2Label.Text = 'Edit Field2';

              % Create EditField2
              app.EditField2 = uieditfield(app.UIFigure, 'text');
              app.EditField2.Position = [305.703125 155 100 22];

              % Create Button
              app.Button = uibutton(app.UIFigure, 'push');
              app.Button.ButtonPushedFcn = createCallbackFcn(app, @ButtonPushed, true);
              app.Button.Position = [443 155 100 22];
          end
      end

      methods (Access = public)

          % Construct app
          function app = App4()

              % Create and configure components
              createComponents(app)

              % Register the app with App Designer
              registerApp(app, app.UIFigure)

              % Execute the startup function
              runStartupFcn(app, @startupFcn)

              if nargout == 0
                  clear app
              end
          end

          % Code that executes before app deletion
          function delete(app)

              % Delete UIFigure when app is deleted
              delete(app.UIFigure)
          end
      end
  end

Answer 1

[prabhat kumar sharma]

Hi Max,

I understand you are facing issues with your app in visualizing the counter with the timer.

Here are the following suggestions I found in your code snippet.

1. Make sure that the EditField is a Edit Field(Numeric) Component, while EditField2 is a Edit Field (text) Component.
2. Typo in Timer Function Call: You have app.timr.TimerFcn = @(obj,event)incrementTick(app); which should be app.timr.TimerFcn = @(obj,event)incrimentTick2(app); based on your method definitions.
3. Timer Period Mismatch: You mentioned wanting to increment every 0.1 seconds, but your timer is set to a period of 0.5 seconds. You should adjust the 'Period' property of the timer to 0.1.
4. Redundant Timer Start Calls: In your startupFcn, you're calling start(app.timr); twice consecutively, which is unnecessary. A single call is sufficient to start the timer.

Here I am attaching the code snippet

classdef App4 < matlab.apps.AppBase
    % Properties that correspond to app components
    properties (Access = public)
        UIFigure         matlab.ui.Figure
        EditFieldLabel   matlab.ui.control.Label
        EditField        matlab.ui.control.NumericEditField
        EditField2Label  matlab.ui.control.Label
        EditField2       matlab.ui.control.EditField
        Button           matlab.ui.control.Button
    end
    properties (Access = private)
        tickr = 69; % Initial value for incrementing
    end
    properties (Access = public)
        timr; % Timer object
    end

    methods (Access = public)
        function incrimentTick2(app)
            app.tickr = app.tickr + 1;
            app.EditField.Value = app.tickr;
        end
    end

    methods (Access = private)
        % Code that executes after component creation
        function startupFcn(app)
            app.timr = timer('StartDelay', 0, 'Period', 0.1, 'ExecutionMode', 'fixedRate');
            app.timr.TimerFcn = @(obj, event)incrimentTick2(app);
            start(app.timr);
        end

        % Button pushed function: Button
        function ButtonPushed(app, event)
            if strcmp(app.timr.Running, 'off')
                start(app.timr);
            end
            app.EditField2.Value = app.timr.Running;
        end
    end

    % App initialization, component creation, and other methods...
    % Remain unchanged from your original code
end

I hope it helps!