MATLAB connection to Mega2560 at COM9 exists in your workspace. To create a new connection, clear the existing object

% Create Arduino object with necessary libraries

arduinoObj = arduino("COM9", "Mega2560", Libraries = ["I2C", "SPI", "Serial", "Servo"]);

MATLAB connection to Mega2560 at COM9 exists in your workspace. To create a new connection, clear the existing object.

% Configure digital pins D20 and D21

configurePin(arduinoObj, "D20", "DigitalInput"); % D20 as input

configurePin(arduinoObj, "D21", "DigitalOutput"); % D21 as output

% Duration to record data (in seconds)

duration = 10;

% Time interval between consecutive data reads

stepTime = 1;

% Total number of data samples to be recorded

samples = duration / stepTime;

% Initialize array to store data for pin D20

D20Array = zeros(1, samples);

% Initialize dataIndex for storing in the array

dataIndex = 1;

% Start a stopwatch to track time (for the loop)

tObj = tic;

% Collect data in the loop for the specified duration

while toc(tObj) <= duration

% Read the state of pin D20 (DigitalInput)

D20 = readDigitalPin(arduinoObj, "D20");

% Store the read data in the corresponding data array

D20Array(dataIndex) = D20;

% Increment dataIndex

dataIndex = dataIndex + 1;

% Pause for the stepTime interval before the next reading

pause(stepTime);

end

% Convert the recorded data to a timetable for further analysis

% Ensure the name is consistent with what will be used in plotting

ARD_DATA_4 = timetable(seconds((1:samples)*stepTime)', D20Array');

% Plot the recorded data

plot(ARD_DATA_4.Time, ARD_DATA_4.Var1); % Use the correct variable name 'Var1' or whatever name the timetable has for the data

title('Recorded Data from Pin D20');

xlabel('Time (s)');

ylabel('Amplitude (0 or 1)');

grid on;

Answer 1

[Manish]

Hi,

I understand that you're facing an error when connecting audio with MATLAB.

I assume that a previous connection was established with the device, and since that connection was not overridden, you are now encountering this error.

To clear the existing object from the workspace, use the 'clear' command.

Here is a sample code:

% Clear any previous Arduino connection
if exist('arduinoObj', 'var')
    clear arduinoObj;
end

% Create Arduino object with necessary libraries
arduinoObj = arduino("COM9", "Mega2560", Libraries = ["I2C", "SPI", "Serial", "Servo"]);

For better understanding, refer to the documentation link below:

• https://www.mathworks.com/help/parallel-computing/clear.html

Hope it helps!