I'm kinda curious about something I noticed last night as I was testing my Arduino 0019 IDE setup on a "new" computer I built for my shop...
My Arduino currently has set up a "test rig" for testing a piece of software for my robot work on it (and its been a while since I last touched it - ouch), so I didn't want to take it apart, and I just wanted to make sure stuff was uploading right. My test rig has a couple of LEDs on it - one inline on pin 13 (with a current limit resistor, of course), and another on pin 9 (with resistor), and the third on some other pin (with resistor), plus there's a potentiometer connected to an analog input pin as a voltage divider; a very simple testing rig.
The last sketch I had on my Arduino was the Blink example (I typically re-flash my board to it after "playing" - so it was the last one I put on after I set up 0019 on my main workstation); when I used my newly constructed box to upload to the board, it seemed to upload OK, no errors...blinking both LEDs on pin 13 (the one on-board the Arduino, plus my "external" extra LED).
So then I wanted to "make sure" it was working OK - so I uploaded the Fade example, but I changed it to pin 13 instead of pin 9 (as it is by default). When I uploaded it - the pin 13 LED blinked...? Like it was still running the blink example...
I had changed the code because I just wanted to see something simple, and I wasn't sure (at the time) what pins the other LEDs were on, and I didn't want to change the connections (because it was my test rig) if one of the extra LEDs wasn't connected to pin 9. Looking at the board again, though, I saw that pin 9 was connected to one of my external LEDs (as I noted above); so I reset the code, uploaded it (no errors again), and...
There it was - the LED fading in and out, like it was supposed to.
Now, at this point, I was pretty satisfied that everything was set up OK, and I could be content that I had the majority of what I needed set up on my simple shop computer the way I wanted it.
I still wonder, though - why did pin 13 blink when using Fade, but pin 9 didn't? Could it be the extra LED (and current limiting resistor) I had on the pin? I imagine I could try to disconnect my extra LED and see if the on-board LED does fade properly...
Was I drawing too much current or something, and the blinking I was seeing was the result of the Arduino resetting...? It just has my curiosity piqued, I guess...
