Editing Blinking Blues Quick Version

= Blink Broken =

The blink program ( lightly modified ) gives unexpected results.


Reduced version of issues raised at 
* [[Blinking Blues]]
* Arduino Forum  http://forum.arduino.cc/index.php?topic=445889.0  

= The Code =

The code in its entirety is: 

<pre>

const int ledPin=6;

void setup() {
  pinMode(ledPin, OUTPUT);
}

void loop() {
   while ( true ) {
       digitalWrite( ledPin, HIGH );   // turn the LED on 
       delayMicroseconds( 5000 );      // wait 
       digitalWrite( ledPin, LOW );    // turn the LED off
       delayMicroseconds( 5000 );      // wait 
    }
}

</pre>

= Results =

In the gif below focus on channel 3, that is pin6  The cursor measurement for 1,2,3,4 are all about 10.1 ms, a value which seems "right".  But at cursor 5,6 you can see a pulse of period 11.060 ms.  This is the "glitch" ( bad term here ) that I am talking about.  It repeats about every 80 ms.  This sort of behavior with some different details has been present in every test I have conducted.

I did look at the rise and fall time on my scope, it is about 20 ns.  I cannot catch this stretched pulse on my scope, but looking for a 1 ms discrepancy across 80 ns is not really easy on a scope.  I did use the single sweep option and mess with a bunch of the variables.  Right now I trust the logic analyzer for this more than the scope, you can try to present an argument for why I should not.  I have to confess I have not tried my old 100 mhz analog scope on this guy.


[[File:BE_1.gif]]