Displaying Value beside graph

Question

Mark Rodger 2018-12-8

0
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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/434642-displaying-value-beside-graph

回答： sMall 2020-1-28

I've typed up a code that displays the time and freqeuecny domain of a signal from an arduino in real time. I would like to display the live value of the freqeuecny domain (FFT) beside the graph/same window or in separate window. Any suggestions?

clear all
ar = serial('COM6','BaudRate',9600);
Fs = 50;
try
    fopen(ar);
catch err
    fclose(instrfind);
    error('Make sure you select the correct COM Port where the Arduino is connected.');
end
Tmax = 20; % Total time for data collection (s)
Ts = 0.001; % Sampling time (s), it correspond to 1000Hz
i = 0;
data = 0;
t = 0;
x_label_names = {'Time (s)', 'Frequency (Hz)'};
subplot(2,1,1)
h = animatedline;
xlabel('Time (s)')
ylabel('Amplitude (mV)')
tic % Start time
while toc <= Tmax
    i = i + 1;
% Fill the data matrix with the data read from arduino
    data(i) = fscanf(ar,'%d');
    % If matlab read the data faster than the sampling rate set in arduino, force sampling to be the same as the
    % sampling time set in matpab code, If matlab is reading slower, nothing can be done.
    t(i) = toc;
    if i > 1
        T = toc - t(i-1);
        while T < Ts
            T = toc - t(i-1);
        end
    end
    t(i) = toc;
    for k = 1:length(t(i))
    addpoints(h,t(i),data(i));
    [timeLogs,voltLogs] = getpoints(h);
    nfft = length(voltLogs);    %length of domnain signal
    nfft2 = 2.^nextpow2(nfft);    %lenght of signal in power of 2
    ff = fft(voltLogs,nfft2);
    fff = ff(1:nfft2/2);
    xfft = Fs.*(0:nfft2/2-1)/nfft2
    subplot(2,1,2)
    plot(xfft,abs(fff));
    xlabel('Frequency (Hz)')
    ylabel('Amplitude (mV)')
    drawnow;
    end
end

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Answer 1

Koundinya 2018-12-14

0
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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/434642-displaying-value-beside-graph#answer_352322

在 MATLAB Online 中打开

The value can be displayed in the figure title, legend or the axis label. You could format the variable to be displayed into a string using sprintf.

for k = 1:length(t(i))
    addpoints(h,t(i),data(i));
    [timeLogs,voltLogs] = getpoints(h);
    nfft = length(voltLogs);    %length of domnain signal
    nfft2 = 2.^nextpow2(nfft);    %lenght of signal in power of 2
    ff = fft(voltLogs,nfft2);
    fff = ff(1:nfft2/2);
    xfft = Fs.*(0:nfft2/2-1)/nfft2
    subplot(2,1,2)
    plot(xfft,abs(fff));
    
    % Value to be displayed
    value_string=sprintf('Frequency(Hz) = %d',xfft);
    
    % Display the updated value in x-axis label
    xlabel(value_string);
    
    % Or Display the updated value in the title
    title(value_string);
    
   %xlabel('Frequency (Hz)')
    ylabel('Amplitude (mV)')
    drawnow;
    end