Arduino/ Matlab interface for real time measurements. How to fix a time step? n

I am using an arduino uno to collect real time sensing data. Below is my MATLAB code. (some steps are commented out due to going from a 4 cell to 1 cell detector.)

interv= 100; passo= 1 t=1 w_n2=0 %x5=0 %y5=0 %z3=0 while (t< interv); t=[0:0.01]'; b=readVoltage (a, 'A0') ; %c=readVoltage(a, 'A1'); %d=readVoltage(a, 'A2'); %e=readVoltage(a, 'A3'); w_n2= [w_n2,b]; %x5 = [x5,c]; %y5 = [y5,d]; %z3 = [z3,e]; hold on plot(w_n2, 'r'); %plot(x4, 'y'); %plot(y4, 'r'); %plot(z3, 'b'); axis ([0, interv, 0,1]); grid t= t+ passo; drawnow; end

However, it seems that each trial I take, the time step is longer than the previous trial. I am not sure if this is due to slowness of my operating system or if there is a way to time step around this. Any help is appreciated!

thanks, maggie

[Madhu Govindarajan]

Have you tried using animated line - http://www.mathworks.com/help/matlab/ref/animatedline.html

Other things that might help are -

1) Remove the grid line as it gets executed on every loop 2) the readVoltage command itself has a few milliseconds of delay as the communication takes sometime, so try not having so many calls.