How can I display on a figure's title block data as the code is running? I was able to do it for time, but struggling to show BPM

clear all;
a= arduino('COM3','Uno');
b=readVoltage(a,'A0'); 
x=2.4;
bc=1;
fs=30;
beat_count=0;
t=[];
tic;
for k=1:100;
toc<2;
b=readVoltage(a,'A0');
x=[x,b];
t=[t;toc];
hP1.XData=t;

plot(x,'ro-');
title(sprintf('t=%g[s],[BPM]= %g',t(end), c(end)));
xlabel('Samples');
ylabel('Electrical Activity');
grid on;    
drawnow;
hold on;

for k=2:length(x)-1;
if( x(k)> x(k-1) & x(k)> x(k+1) & x(k)>1);
bc = (bc + 1 );
c =  (bc*fs)/(60*length(x));

end
end
end

Answer 1

[Walter Roberson]

Generally speaking the line

title(sprintf('t=%g[s],[BPM]= %g',t(end), c(end)));

looks plausible. However, you have not initialized c at that point: you do not set c until the for/if sequence after that (and that sequence will not always assign a value to c either.) You are also expecting c to be an array when you use c(end), but you look like you are only assigning a scalar to it.

Note: it would look to make more sense to

plot(t, x)

Assigning t to hP1.XData does nothing because hP1 has not been defined or used elsewhere. If you are expecting that hP1 is the handle to a plot, then note that your plot(x,'ro-') would generate a new line rather than update an existing line. With the 'hold on" in effect, it looks like you are continually re-drawing over existing areas.

You should consider using animatedLine() instead of the way you are plotting now.

hP1 = animatedline();

for ...
  ...
  addpoints(hP1, t, b);
  drawnow update
  ...
end