App Designer and Arduino

Hi,

I am designing an interface in the App Designer. I have an Arduino board connected to some sensors. I would like to be able to run the interface multiple times, but right now I run it once perfectly and when I click run again it tells me I have an existing connection at my COM port and I need to clear it. I am unsure how to do this as I am very new to app designer! Any help would be greatly appreciated!

Thanks!

[Asad Mirza]

Mind posting some of app designer code for us?

I suspect what is happening is you're trying to connect to the arduino each time you say click a button to send a signal or something. What you should do instead is connect to the arduino once and then when you click the button to do something have the button code only send a signal rather than try to connect to the arduino.

I'd like to help more but I would need to see the code as it is first.

[Allison McCrady]

classdef app2 < matlab.apps.AppBase

    % Properties that correspond to app components
    properties (Access = public)
        UIFigure               matlab.ui.Figure
        RUNButton              matlab.ui.control.Button
        STOPButton             matlab.ui.control.Button
        UIAxes                 matlab.ui.control.UIAxes
        COMPortEditFieldLabel  matlab.ui.control.Label
        COMPortEditField       matlab.ui.control.EditField
        SaveAsEditFieldLabel   matlab.ui.control.Label
        SaveAsEditField        matlab.ui.control.EditField
    end

    
    properties (Access = private)
        stop;
        port;
        done=0;
        timeLogs;
        forceLogs;
        timeSecs;
        filename;
        T;
        h;
        a;
    end


    methods (Access = private)

        % Code that executes after component creation
        function startupFcn(app, a)
            app.a=app.a;
        end

        % Value changed function: COMPortEditField
        function COMPortEditFieldValueChanged(app, event)
            value = app.COMPortEditField.Value;
            app.port=value;
        end

        % Button pushed function: RUNButton
        function RUNButtonPushed(app, event)
            app.a=arduino(app.port,'uno');
            
            figure
            app.h=animatedline;
            ax=gca;
            ax.YGrid='on';
            ax.YLim=[0 100];
            
            app.stop=false;
            starttime=datetime('now');
            
            while ~app.stop
                % Read current voltage value
                voltage1 = readVoltage(app.a,'A0');
                voltage2 = readVoltage(app.a,'A1');
                %     Calculate force from voltage (based on data sheet)
                %     Flipped for ease of use
                force1=-(13.499*voltage1)+68.534; %from calibration with standard weights
                force2=-(9.9586*voltage2)+49.882; %from calibration with standard weights
                force=force1+force2;
                % Get current time
                t = datetime('now') - starttime;
                % Add points to animation
                addpoints(app.h,datenum(t),force)
                % Update axes
                ax.XLim = datenum([t-seconds(15) t]);
                datetick('x','keeplimits')
                drawnow
                % Check stop condition
                app.stop = app.done;
            end
            
        end

        % Button pushed function: STOPButton
        function STOPButtonPushed(app, event)
            app.done=1;
            [app.timeLogs,app.forceLogs] = getpoints(app.h);
            app.timeSecs = (app.timeLogs-app.timeLogs(1))*24*3600;
            app.T = table(app.timeSecs',app.forceLogs','VariableNames',{'Time_sec','Force_N'});
            % Write table to file
            writetable(app.T,app.filename)
            
            [app.timeLogs,app.forceLogs] = getpoints(app.h);
            app.timeSecs = (app.timeLogs-app.timeLogs(1))*24*3600;
            plot(app.UIAxes,app.timeSecs,app.forceLogs) 

        end

        % Value changed function: SaveAsEditField
        function SaveAsEditFieldValueChanged(app, event)
            value = app.SaveAsEditField.Value;
            app.filename=value;
        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';

            % Create RUNButton
            app.RUNButton = uibutton(app.UIFigure, 'push');
            app.RUNButton.ButtonPushedFcn = createCallbackFcn(app, @RUNButtonPushed, true);
            app.RUNButton.BackgroundColor = [0 1 0];
            app.RUNButton.Position = [388 22 100 31];
            app.RUNButton.Text = 'RUN';

            % Create STOPButton
            app.STOPButton = uibutton(app.UIFigure, 'push');
            app.STOPButton.ButtonPushedFcn = createCallbackFcn(app, @STOPButtonPushed, true);
            app.STOPButton.BackgroundColor = [1 0 0];
            app.STOPButton.Position = [509 22 100 31];
            app.STOPButton.Text = 'STOP';

            % Create UIAxes
            app.UIAxes = uiaxes(app.UIFigure);
            title(app.UIAxes, 'Force vs. Time')
            xlabel(app.UIAxes, 'Time')
            ylabel(app.UIAxes, 'Force')
            app.UIAxes.YGrid = 'on';
            app.UIAxes.Position = [11 72 619 398];

            % Create COMPortEditFieldLabel
            app.COMPortEditFieldLabel = uilabel(app.UIFigure);
            app.COMPortEditFieldLabel.HorizontalAlignment = 'right';
            app.COMPortEditFieldLabel.Position = [44 52 59 22];
            app.COMPortEditFieldLabel.Text = 'COM Port';

            % Create COMPortEditField
            app.COMPortEditField = uieditfield(app.UIFigure, 'text');
            app.COMPortEditField.ValueChangedFcn = createCallbackFcn(app, @COMPortEditFieldValueChanged, true);
            app.COMPortEditField.Position = [118 52 100 22];
            app.COMPortEditField.Value = 'Com';

            % Create SaveAsEditFieldLabel
            app.SaveAsEditFieldLabel = uilabel(app.UIFigure);
            app.SaveAsEditFieldLabel.HorizontalAlignment = 'right';
            app.SaveAsEditFieldLabel.Position = [45 12 54 22];
            app.SaveAsEditFieldLabel.Text = 'Save As:';

            % Create SaveAsEditField
            app.SaveAsEditField = uieditfield(app.UIFigure, 'text');
            app.SaveAsEditField.ValueChangedFcn = createCallbackFcn(app, @SaveAsEditFieldValueChanged, true);
            app.SaveAsEditField.Position = [114 12 214 22];
        end
    end

    methods (Access = public)

        % Construct app
        function app = app2(varargin)

            % Create and configure components
            createComponents(app)

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

            % Execute the startup function
            runStartupFcn(app, @(app)startupFcn(app, varargin{:}))

            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

This is the entire code for the app designer. I think the arduino connection is in the Run button function. I attached a photo of the interface as well for reference! Thank you!

[Mohammed Yakoob]

Hello dear You can use a= arduino(com, Uno); For example to connect and in the another callback a=[]; to clear the port for new connection.

Answer 1

[Asad Mirza]

You could try changing your startup to just this instead.

        function startupFcn(app, a)
            app.a=arduino(app.port,'uno');
        end

Now remove the arduino(app.port,'uno'); line from your RUNButtonPushed(app, event) function.

This way you only create the arduino object once when you startup the app and then after that all you do is send signals with the button. I do not have an arduino nearby to test this on unfortunately.

[Allison McCrady]

See the problem with that is that they need to identify the com port and having it in the startup function doesnt allow that. Do you know if I can write the app to search for the com port? THat would be best. Thanks!

[Asad Mirza]

Attached you'll find a quick app I wrote that first finds all available COM ports. You then select the port your arduino is connected to from the list and then press connect to link it to the arduino. You can edit this app such that now that you've connected to the Arduino separatly you can do all the plotting afterwards.

I suggest you make like a button on the app that now plots data from any of the input arduino pins but only after you've connected. You can use the uibuton enable property to make plotting impossible unless you've already connected to an arduino.

[Santiago Restrepo Estrada]

Hello,

I was wondering how could I integrate this into an existing app.

thank you

Answer 2

[Kihak Lee]

Dear Asad Mirza

I tested your attached files(Arduino_Ex.mlapp) several times. There is a problem in disconnect button.

When push disconnect button, error is happend. I can not fix it.

Plese check your code!

thanks