I'm getting extra blinks at regular intervals when running simple LED programs

This is my first post here, thanks in advance for any help or advice. I’m excited to learn (and work with my teenage son in the process…). I really appreciate everyone that is willing to take time to help out a greeny.

I’ve just started learning Arduino with very minimal electronics background. I’m studying from “Arduino Projects for Dummies” and the “Sheepdogguides.com” website. I’ve tried writing several simple sketches for lighting LED’s, and also inputing a few simple LED sketches from these sources. They seem to load fine and execute correctly, but regardless of what I try, at approximately five second intervals I get quick multiple blinks from one of the LED’s. Other than that, the code runs fine. This extra blinking is always synchronized with the blinking of the LED marked “L” on the Arduino board.

This seems somehow associated with the “Blink” program that comes loaded on the Arduino but my understanding is that “Blink” should be overwritten when uploading any sketch.

I’ve tried this with several different sketches and get the same result.

Any thoughts or advice?

escobadelmar:
This seems somehow associated with the "Blink" program that comes loaded on the Arduino but my understanding is that "Blink" should be overwritten when uploading any sketch.

Blink is indeed overwritten and thus the problem is not associated with the Blink program. However, when the Arduino's bootloader runs it does a sequence of rapid blinks. The bootloader runs every time there is a hardware reset of the Arduino. So if there is some problem that is causing a momentary power loss to your Arduino this would cause the bootloader blink behavior to occur repeatedly. You could identify if this is happening by adding some sort of unique behavior to your setup() code that will identify when your program starts. This could be a specific blink sequence different from the action of the LED in the rest of your code or it could be a print to the Serial Monitor. For example:

void setup() {
  Serial.begin(9600);
  Serial.println("started");
}

Pert,

I just plugged into an external power supply and the problem is gone! Thank you very much for a quick and very informative answer. I was using my usb connection from my macbook pro for the power supply. I guess I won’t be doing that any more.

Thanks again!

escobadelmar