How can I read values from an ultrasonic sensor connected to an Arduino in Matlab app designer?

The problem is mainly getting the measured distance and display as I want. I do not get any errors when ruuning the app but no distance is shown on the editable field. Below is some of the code I have used for the button as well as the editable numeric field. I believe there is something I am missing and I cannot figure it out, please let me know of any suggestion I can try out to get this right.

  
    properties (Access = private)

Unrecognized function or variable 'private'.

        a
        u 
        dist
    end

I have declared the above properties which I will be using in the code to further try and attain the measured distance and display it in an editable numeric field

        function startupFcn(app)
            app.a = arduino;
            app.u = ultrasonic(app.a,'d50','d51');
        end

Above is the start up function whereby I have assignedd values to the variables I declared earlier on. Where app.a= arduino gets all the required properties and makes the neccessary connections and settings to allow me to communicate with the arduino board. app.u = .... lets me define the pins on the arduino board which will be used as triger and echo pins.

        function ButtonPushed(app, event)
            
           % app.u = ultrasonic(app.a,'D50','D51');

            app.dist  = readDistance(app.u); % determing the initial distance
            while (app.dist > 0.050) % this loop ensures that the sensor continues to 
                                     % "measure" distance for as long as the object is further than 5cm
                  app.dist = readDistance(app.u);    
            end
        end
        

Below is the last piece of code which I am using to try and display the measured distance

        function EditFieldValueChanged(app, event)
            app.EditField.Value = app.dist;      
        end

Answer 1

[Walter Roberson]

EditFieldValueChanged is only invoked when the user edits the field. You need to update the field as you store new app.distance values. You might need a

drawnow limitrate

to allow the display to update

[Mmakgabo Masipa]

Thank you for your assistance.

Answer 2

[xochitl berenice]

Hello, I have the same problem right now. Could you solve it?

Answer 3

[MathWorks MATLAB Hardware Team]

Hi

Thanks for reaching out to us.

Based on your description, it seems like you want to display the distance measurement in an edit field upon clicking a push button. If that's the case, I suggest trying out the following code snippet within your ButtonPushed callback function:

function ButtonPushed(app, event)
% app.u = ultrasonic(app.a,'D50','D51');
app.dist = readDistance(app.u); % Determine the initial distance
app.EditField.Value = app.dist; % Update the Edit field
while (app.dist > 0.050) % Continue measuring distance as long as the object is more than 5cm away
    app.dist = readDistance(app.u);    
end
end

Please feel free to contact us if you need any further assistance,

https://in.mathworks.com/support/contact_us.html

Best Regards,

MATLAB Hardware Team

MathWorks