Arduino clearing existing connection issue
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I have declared a global object arduino() and in a different function I would like to clear this connection and create another. It keeps saying that the connection to arduino is existing eventhough I use "clearvars -global a".
Error: "MATLAB connection to Uno at COM3 exists in your workspace. To create a new connection, clear the existing object."
function ClearArduino(app)
clearvars -global a
a = arduino('COM3', 'Uno'); %Error is on this line
writeDigitalPin(a, 'D11', 0);
writeDigitalPin(a, 'D12', 0);
writeDigitalPin(a, 'D13', 0);
end
function runArduinoCode(app, indicator)
clearvars -global a
a = arduino('COM3', 'Uno');
while indicator == "On"
writeDigitalPin(a, 'D11', 1);
pause(0.5)
writeDigitalPin(a, 'D11', 0);
writeDigitalPin(a, 'D12', 1);
pause(0.5)
writeDigitalPin(a, 'D12', 0);
writeDigitalPin(a, 'D13', 1);
pause(0.5)
writeDigitalPin(a, 'D13', 0);
end
clear a;
end
1 comentario
Laura Letellier
el 28 de Abr. de 2021
Editada: Laura Letellier
el 28 de Abr. de 2021
Did anyone ever find a solution for this?
My students are encountering this issue and the only way we can 100% clear the existing object is to exit MATLAB, unlpug the Arduino, replug, and restart MATLAB.
If any of the MATLAB software developers are monitoring this, please tell us how to even see the workspace when using App Designer and then give us a hint as to how to clear the connection. Since you are throwing the error you must have some way to access the associated pointer, handle, or hwind to know that the connection is unavailable. If so there must be a way for us to programmatically release it.
Thank you!
Respuestas (2)
Geoff Hayes
el 21 de Jun. de 2019
Editada: Geoff Hayes
el 21 de Jun. de 2019
Borian - why not define a property in your app that represents the arduino object so that all callbacks have access to it? See Share Data Within App Designer Apps for details. Presumably you would do something like
properties (Access = private)
arduinoObject = [] % arduino object
end
and your callbacks (?) would become something like
function ClearArduino(app)
if ~isempty(app.arduinoObject)
clear(app.arduinoObject);
end
app.arduinoObject = arduino('COM3', 'Uno');
writeDigitalPin(app.arduinoObject, 'D11', 0);
writeDigitalPin(app.arduinoObject, 'D12', 0);
writeDigitalPin(app.arduinoObject, 'D13', 0);
end
function runArduinoCode(app, indicator)
if ~isempty(app.arduinoObject)
clear(app.arduinoObject);
end
app.arduinoObject = arduino('COM3', 'Uno');
while indicator == "On"
writeDigitalPin(app.arduinoObject, 'D11', 1);
pause(0.5)
writeDigitalPin(app.arduinoObject, 'D11', 0);
writeDigitalPin(app.arduinoObject, 'D12', 1);
pause(0.5)
writeDigitalPin(app.arduinoObject, 'D12', 0);
writeDigitalPin(app.arduinoObject, 'D13', 1);
pause(0.5)
writeDigitalPin(app.arduinoObject, 'D13', 0);
end
end
I have no idea if the above will work but it may be something to start with.
3 comentarios
shaherbano zaidi
el 15 de Sept. de 2023
I was encountering the same issue i just added "Clear all' at the top of my code.
0 comentarios
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