Arduino ReadDigitalPin all ones

Hi, I'm trying to connect an arduino to matlab to collect data from the digital pins. I am sending data to pin D3, but when I say readDigitalPin(a,'D3') in matlab it just gives me 1. My code is below, any advice would be appreciated.

if true
  a = arduino('com8', 'uno');
t1 = 0;
dt=[];
dv=[];
tic
for i =1:500
  i;
  tic;
  v = readDigitalPin(a,'D2');
  dT = toc;
  t1 = t1 + dT;
  dt(i) = [t1];
  dv(i) = [v]
  pause(0.5)
end

end

[Walter Roberson]

Have you put an oscilloscope onto the pin to verify that the value goes lower than the threshold at some point, and does so for longer than the hold time of the sampling hardware?

Is D2 configured as a continual read or is it configured as triggered by edge detection? If triggered then what are the reset conditions?