Help debugging real time plotting issues

I am plotting Raw EMG data in MATLAB. Here is the code I am using for plotting after creating time vector.

% Function to update the real-time plots

function updatePlots(t, data)

if isvalid(fig)

% Create time vectors

tData = (1:length(data)) / samplingRate; % Create a time vector for the raw data

% Plot raw data

addpoints(h1, tData , data);

% Set the X-axis limits based on the time window

xlim(ax1, [t - timeToEdit.Value / 1000, t]);

drawnow limitrate;

end

end

end

Why does the plot have lines connected to the first datapoint. How do I go about debugging this

Answer 1

[Voss]

"Why does the plot have lines connected to the first datapoint[?]"

Because tData(1) is always 1/samplingRate.

I guess you should be using t in your calculation of tData, but I can't say for sure how because I don't know what t represents. I gather it's a scalar number since otherwise the call to xlim would produce an error. You use t as the upper x-limit of your axes, so is it the end time in seconds of the new data? If so then maybe something like this:

tData = t - (numel(data)-1:-1:0) / samplingRate;

[Harini]

Hi Voss, thanks for your answer. The lines from origin have disappared but now there are lines connecting random points. Not sure why. There is a timer running used to plot amplitude vs time of the EMG data received from Arduino. The timer runs from 0 to t, where t is the elapsed time when data x is acquired from arduino. The data read from arduno is alright. It seems to be an issue with plotting.

% Start reading and processing data

while isAcquiringData

data = readline(arduinoObj);

data = str2double(data);

% Append data to buffers

dataBuffer = [dataBuffer, data];

% Update elapsed time

t = toc(startTime);

% Debugging: Display received data

%disp(['Received data: ', num2str(data)]);

% Check if the time window has elapsed

if t >= timeToEdit.Value / 1000

stopButtonPushed();

end

% Update real-time plots

updatePlots(t, dataBuffer);

end

end

end