Unable to perform assignment because the size of the left side is 1-by-1 and the size of the right side is 0-by-0.

if ~isempty(instrfind)
     fclose(instrfind);
      delete(instrfind);
end 

A = zeros(64,1);
B = zeros(64,1);
C = zeros(64,1);
D = zeros(64,1);

Arduino=serial('COM3','BaudRate',9600);%!!!!!!!!need to change the port for windows!!!!!!
fopen(Arduino); 
writedata=uint16(500); %0x01F4
fwrite(Arduino,writedata,'uint16') %write datac

for s = 1:1
    
        for i=1:64 %read 64 lines of data
        %A(i,1) = fscanf(Arduino,'%f')
        A(i,1) = fscanf(Arduino,'%f');
        end
        B = A;
        D(1,1) = abs(B(3,1)-B(4,1));
        D(2,1) = abs(B(4,1)-B(5,1));
        D(3,1) = abs(B(5,1)-B(6,1));
        D(4,1) = abs(B(6,1)-B(7,1));
        D(5,1) = abs(B(7,1)-B(8,1));
        D(6,1) = abs(B(12,1)-B(13,1));
        D(7,1) = abs(B(13,1)-B(14,1));
        D(8,1) = abs(B(14,1)-B(15,1));
        D(9,1) = abs(B(15,1)-B(16,1));
        D(10,1) = abs(B(16,1)-B(9,1));
        D(11,1) = abs(B(17,1)-B(18,1));
        D(12,1) = abs(B(21,1)-B(22,1));
        D(13,1) = abs(B(22,1)-B(23,1));
        D(14,1) = abs(B(23,1)-B(24,1));
        D(15,1) = abs(B(24,1)-B(17,1));
        D(16,1) = abs(B(25,1)-B(26,1));
        D(17,1) = abs(B(26,1)-B(27,1));
        D(18,1) = abs(B(30,1)-B(31,1));
        D(19,1) = abs(B(31,1)-B(32,1));
        D(20,1) = abs(B(32,1)-B(25,1));
        D(21,1) = abs(B(33,1)-B(34,1));
        D(22,1) = abs(B(34,1)-B(35,1));
        D(23,1) = abs(B(35,1)-B(36,1));
        D(24,1) = abs(B(39,1)-B(40,1));
        D(25,1) = abs(B(40,1)-B(33,1));
        D(26,1) = abs(B(41,1)-B(42,1));
        D(27,1) = abs(B(42,1)-B(43,1));
        D(28,1) = abs(B(43,1)-B(44,1));
        D(29,1) = abs(B(44,1)-B(45,1));
        D(30,1) = abs(B(48,1)-B(41,1));
        D(31,1) = abs(B(49,1)-B(50,1));
        D(32,1) = abs(B(50,1)-B(51,1));
        D(33,1) = abs(B(51,1)-B(52,1));
        D(34,1) = abs(B(52,1)-B(53,1));
        D(35,1) = abs(B(53,1)-B(54,1));
        D(36,1) = abs(B(58,1)-B(59,1));
        D(37,1) = abs(B(59,1)-B(60,1));
        D(38,1) = abs(B(60,1)-B(61,1));
        D(39,1) = abs(B(61,1)-B(62,1));
        D(40,1) = abs(B(62,1)-B(63,1));
        Hom(:,s) = D;
end

Currently facing this error. We are trying to read 3V input from mux via Arduino .Please help.

Unable to perform assignment because the size of the left side is 1-by-1 and the size of the right side is 0-by-0.

[hosein Javan]

that means the right side is empty. no data has been read or the data is lost. check again matrix "B"

Answer 1

[VBBV]

for i=1:64 %read 64 lines of data
      %A(i,1) = fscanf(Arduino,'%f')
      %A(i,1) = fscanf(Arduino,'%f');
A(i,1) = read(Arduino,64,"uint16")
end

As you are trying to read data from serial port device, Matlab recommends to use read function instead of fscanf to read data. fscanf seems a better option to read data from files. The matrix B seems to be empty since nothing has been read. It also appears, that serial function is not recommended by Matlab.

[Walter Roberson]

you would only use read() if you switch to serialport()

In this kind of situation you would readline() and sscanf() or potentially str2double(). read() is binary read like fread() not like fscanf