Need help with storing live data from sensors into array

this is my code. I want to store the incoming data into my array/matrix whichever would do the trick. This keeps overwriting the previous data into the array. I want the data to be added up at the bottom.

I am also getting this problem. "Conversion to cell from uint16 is not possible."

iterate = 0;

while 1

iterate =plus(iterate, 1); %counter

disp(iterate);

Gyro_X = readRegister(MPU9250, GYRO_XOUT_H, 'uint16')

Gyro_Y = readRegister(MPU9250, GYRO_YOUT_H, 'uint16')

Gyro_Z = readRegister(MPU9250, GYRO_ZOUT_H, 'uint16')

pause(1/10);

%Gyro = table(iterate, Gyro_X, Gyro_Y, Gyro_Z);

Gyro = {};

Gyro(i) = [ iterate, Gyro_X, Gyro_Y, Gyro_Z];

end

Answer 1

[Mustafa Abu-Mallouh]

If you want to store the values in each row, call out that you want the values to take over all columns of "Gyro". See below:

i = 0;
max_data_len = 10;

% Initialize 'Gyro' with desired dimensions
%     - Don't have to but it helps performance
Gyro = zeros( max_data_len , 4 );

while i < max_data_len
    
    i = i+1;
    
    Gyro_X = randi(30,1);
    Gyro_Y = randi(30,1);
    Gyro_Z = randi(30,1);
    
    % If creating a results array
    Gyro(i,:) = [i Gyro_X Gyro_Y Gyro_Z];
    
end

Another issue is you redefine "Gyro" as an empty cell array every iteration of the loop when you call the following code:

  Gyro = {};

This clears the data you originally had stored in the variable. This is also the reason you are getting the "Conversion to cell from uint16 is not possible" error; it is trying to convert your 16 bit integer array into a cell array

[Samuel Louise]

Thank you for your help! Much appreciated.

[Samuel Louise]

Hi,

I am having another problem and it is to do with the time it is taking for MATLAB to take the data from the FIFO. Matlab is processing it in seconds. For example

while i <= 50

i = i+1;

Gyro_X = randi(30,1);

Gyro_Y = randi(30,1);

Gyro_Z = randi(30,1);

% If creating a results array

Gyro(i,:) = [i Gyro_X Gyro_Y Gyro_Z];

end

the problem with 'i' is that 'i' is being read in 50 seconds. Is there anyway i can speed up that process?

Thank you for your help.

Answer 2

[ahmed nebli]

what you need to do is create a vector/matri without defining its size first (e.g.: A=[]; ) then use the command vertcat.

see how this command works : https://www.mathworks.com/help/matlab/ref/vertcat.html

[Samuel Louise]

Hi,

Thank you for the prompt reply. But I have tried to follow what your instructing but it is constantly replacing the old value to the new value in the loop.

I am now getting this error : The RowNames property must be a cell array, with each element containing one nonempty character vector.

After doing this:

Gyro = table([Gyro_X],[Gyro_Y],[Gyro_Z],'VariableNames',{'GYRO_X','GYRO_Y', 'GYRO_Z'},'RowNames',{iterate})