How to plot real time serial data.

Question

Kulbir 2023-4-27

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1954344-how-to-plot-real-time-serial-data

评论： Kulbir 2023-5-1

I want to plot real time raw serial data. the data comes in the form of real(no configureble settings) and is broken into packets with a total length of 9 bytes. AND GETTING the ERROR, PLZ HELP ME OUT

% Set up the serial port connection
serialPort = serialport("COM4", 115200); % Replace "COM1" with the appropriate port name
configureTerminator(serialPort, "LF",10);
% serialPort.Terminator;
% Initialize variables
seqNum = 0;
ch1Data = [];
ch2Data = [];
button1 = 0;
button2 = 0;
% Continuously read data packets from the USB port
while true
    % Read a packet from the serial port
    packet = read(serialPort, 9, "uint8");
    
    % Verify that the packet start byte is correct
    if packet(1) ~= hex2dec("59")
        continue; % Packet start byte is incorrect, skip to next packet
    end
    
    % Extract data from the packet
    seqNumPacket = packet(2);
    ch1Packet = typecast(uint8(packet(3:5)), "int8");
    ch2Packet = typecast(uint8(packet(6:8)), "int8");
    statusByte = packet(9);
    
    % Check for button presses
    button1 = bitget(statusByte, 7);
    button2 = bitget(statusByte, 6);
    
    % Check that the sequence number is correct
    if seqNumPacket ~= seqNum + 1
        % Sequence number is incorrect, data may be out of order or lost
        % You may want to add error handling or logging here
    end
    
    % Update variables with new data
    seqNum = seqNumPacket;
    
    ch1Data(end+1) = ch1Packet;
    ch2Data(end+1) = ch2Packet;
    
    % Do something with the data
    % ...
end

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Answer 1

cdawg 2023-4-28

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在 MATLAB Online 中打开

The entire error is cut off in your screenshot, but it looks like you're trying to assign a vector into ch1Data(end+1) which only accepts a scalar. I don't know what "packet" actually is in your script, so I'll make one up:

ch1Data = [];
packet = [2 3 1 6 3 9 0];
ch1Packet = typecast(uint8(packet(3:5)), "int8")
ch1Packet = 1×3
   1   6   3
ch1Data(end+1) = ch1Packet
Unable to perform assignment because the indices on the left side are not compatible with the size of the right side.

Instead, you can try something like this:

ch1Data = [ch1Data ch1Packet] % or if ch1Packet is a column vector in your real case, do ch1Data = [ch1Data; ch1Packet]

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Kulbir 2023-5-1

Hi @cdawg, Thank you for your answer.

I am getting the ouput in command window in digit form. It would be so helpful if you suggest me how i can draw the real time data(speech signal) in plotting graph. my recording taken would be like 10 seconds. thank you

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