MATLAB: Hi all! Could you please help me understand this piece of code here

Question

%% setup

hold all

a = arduino('COM3', 'Uno');

mpu = i2cdev(a,'0x68'); %mpu adress is normally 0x68

writeRegister(mpu, hex2dec('B6'), hex2dec('00'), 'int16'); %reset

data = zeros(10000,14,'int8'); %prelocating for the speed

j = 1;

a1 = animatedline('Color',[1 0 0]);

a2 = animatedline('Color',[0 1 0]);

a3 = animatedline('Color',[0 0 1]);

legend('Accel_x','Accel_y','Accel_z')

%% loop

while(true)

x=1;

for i=59:72 % 14 Data Registers for Accel,Temp,Gyro

data(j,x) = readRegister(mpu, i, 'int8');

x = x + 1;

end

y = swapbytes(typecast(data(j,:), 'int16')) %if your system is big-endian remove the swapbytes function

addpoints(a1,j,double(y(1)));

addpoints(a2,j,double(y(2)));

addpoints(a3,j,double(y(3)));

j = j+1;

drawnow limitrate

end

Answer 1

It initializes an i2c register on the arduino. It loops indefinitely. Each cycle it reads 14 bytes of data that are in big-Endian order. It rearranges the data to be 16 bit little-Endian signed 16 bit integers. It takes the first three of those and adds them to the plot and ignores the rest.

After 10000 points it will slow down a lot for memory allocation reasons.

The code could be trimmed a bit, such as not reading the values it is not going to use.