title: Arduino pulseIn returns weird values
body: <p>I'm trying to connect my arduino board to my RC receiver. I have the receiver powered using a pretty standard 4xAA pack, and I have one channel of the receiver connected to port 7 on the arduino (I've tried several different pins for this). The code below just returns numbers in the range of 8000 (sometimes 9000 and sometimes 7000), but this doesn't change when I apply controls from the transmitter to the channel. What's weirder is that the numbers return even when the wire to port 7 is unplugged from the receiver (but still attached to the arduino). Does this make sense? Any thoughts?</p>
  
  <pre><code>int pin = 7;
  unsigned long duration;
  
  void setup()
  {
    pinMode(pin, INPUT);
    Serial.begin(9600); // Pour a bowl of Serial
  }
  
  void loop()
  {
    duration = pulseIn(pin, LOW);
    Serial.print("Channel 1:"); // Print the value of 
    Serial.println(duration);        // each channel
  }
  </code></pre>