How can i change ascii text from arduino serial port to number in matlab?

Hi, i am trying to receive numbers from arduino serial port. Arduino serial port prints number in ascii text format. But when i am receiving it in matlab using fscanf command i get an ascii equivalent. For example when i print 1 to arduino serial port monitor i receive its ascii equivalent 49 in matlab. At present i am receiving a 1 X 16 element array. Arduino serial port [1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1] = Matlab side [49 49 49 49 49 49 49 49 49 49 49 49 49 49 49 49] In matlab side also i want it to be 1 as entry elements. What should i do i am also open to convert the received array in matlab to 111 after receiving.

%%Create serial object for Arduino
s = serial('COM7'); % change the COM Port number as needed
%%Connect the serial port to Arduino
s.InputBufferSize = 1; % read only one byte every time
%s.baudrate = 9600;
try
    fopen(s);
catch err
    fclose(instrfind);
    error('Make sure you select the correct COM Port where the Arduino is connected.');
end
%%Create a figure window to monitor the live data
Tmax = 6; % Total time for data collection (s)
figure,
grid on,
xlabel ('Time (s)'), ylabel('Data (8-bit)'),
axis([0 Tmax+1 -10 300]),
%%Read and plot the data from Arduino
Ts = 0.3125; % Sampling time (s)
i = 0;
data = 0;
t = 0;
tic % Start timer
while toc <= Tmax
    i = i + 1;
    %%Read buffer data
    data(i) = fscanf(s,'%c');
    %pause(0.1);
    %disp(data(i));
    %%Read time stamp
    % If reading faster than sampling rate, force sampling time.
    % If reading slower than sampling rate, nothing can be done. Consider
    % decreasing the set sampling time Ts
    t(i) = toc;
    if i > 1
        T = toc - t(i-1);
        while T < Ts
            T = toc - t(i-1);
        end
    end
    t(i) = toc;
    %%Plot live data
    if i > 1
        line([t(i-1) t(i)],[data(i-1) data(i)])
        drawnow
    end
end
fclose(s);

Copyright 2014 The MathWorks, Inc.

[Guillaume]

How do your differentiate between sending two consecutive 1s, and sending the number 11?

[Shivam Trivedi]

From the arduino side i am sending decimal numbers separated from comma i.e comma separated values. i wish to use comma as a identifier for differentiating between two numbers and also suggest me how i should go about differentiating between two rows as i am continously sending temperature values from the arduino side i.e continous 16 values separated by new line.

Answer 1

[Guillaume]

If you just want to convert the individual character digits into numbers from 0 to 9, then simply subtract the ASCII code for 0 from all your codes, so:

data(i) = fscanf(s, '%c') - '0';

[Shivam Trivedi]

Thank you very much it works. Now my further question is i am receiving temperature values from arduino using 16 sensors now what i want to do is plot a heatmap of the temperature values. What should be my approach? The temperature values are floating point decimals and i want to receive them in the heatmap dynamically i am using 16 sensors.

[Shivam Trivedi]

This works only for integers but what about the rest of the numbers like suppose i want to receive 23.46 and i have to differentiate it from other sensor reading 24.56 using a comma. How should i identify a comma as separator? i.e i will send 23.47,24.56,25.26,22.16,27.87,26.90,28.75,29.75,25.50,28.50,26.75,22.56,20.15,22.67,23.45,25.13 and want to receive them as 23.47 24.56 25.26 22.16 27.87 26.90 28.75 29.75 25.50 28.50 26.75 22.56 20.15 22.67 23.45 25.13 in a row matrix with 16 column entries. Later i have to plot a heatmap of the same as i am receiving those values with every run.

[Guillaume]

That's a completely different format then you originally stated so of course the solution doesn't work.

I don't think scanf handles comma delimiters, so replace your commas by spaces, then you can trivially read the data with

data(i) = fscanf(s, '%f')

[Shivam Trivedi]

Okay, thanks but again for the decimal points i am getting the ascii equivalent 46 like this 1 46 23 for 1.23. Also when i am removing commas by space i am getting the error as below: In an assignment A(:) = B, the number of elements in A and B must be the same.

Error in serial7 (line 29) data(i) = fscanf(s, '%f');

[Shivam Trivedi]

also in the starting i am getting a value of 255. Do you know of any other probable solution?

[Shivam Trivedi]

apart from fscanf? Can i use fread , fgets? But i have tried them earlier didnt work.

[Guillaume]

The problem is not which function you use, fscanf is just fine, it's that you're not clear over how the data is transmitted. Do you actually send [1 46 23] (decimal values) or [49 46 50 51] (decimal values equivalent to '1.23').

If you are sending character representation of numbers, separated by spaces, e.g. '1.23 2.56', then |fscanf(s, '%f') will work. The only thing I forgot is that you appear to only want to read one number and so have to tell fscanf:

data(i) = fscanf(s, '%f', 1);

[Shivam Trivedi]

yes i am sending character representation of numbers through arduino serial monitor which prints ascii readable text as 1.23 23.46 in the matlab side it is ascii form representation and i want to receive them in a row vector of 16 elements like [23.46 upto 16 entries]

Using data(i) = fscanf(s, '%f', 1), i am again getting same error.

[Shivam Trivedi]

When i am using fscanf(s,'%f') in place of decimal i am getting its ascii equivalent i.e 46. This comes like this Arduino serial monitor 1.23 -> Matlab side 1 46 23 i want it to be 1.23 on the matlab side as well. 2nd challenge is, is it possible to receive 16 numbers at one time in the data matrix and then 2nd set of numbers in the matrix after new line terminator.

[Shivam Trivedi]

Also i am getting these below errors Warning: Unsuccessful read: Matching failure in format.. Warning: Unsuccessful read: The input buffer was filled before the Terminator was reached..