As soon as I plugged my brand new RedBoard (Sparkfun's Uno) into my computer, I saw the onboard LED (for pin 13) blink on and off every 1 second. This was before I even sent the first demo sketch to blink the LED. After I uploaded a sketch to change the blink time, the LED's blink cycle changed as I expected.

But why was the LED blinking before I sent my very first sketch? Is the RedBoard pre-loaded with a sketch?

  • If it's not behaving like you expected it to without a sketch, then I'd say that the answer is yes. Commented May 6, 2014 at 17:56
  • What is the standard behavior for a brand new OOB Uno or RedBoard when it's first connected to power? Does it differ if that power is from the wall or USB?
    – KatieK
    Commented May 6, 2014 at 18:03
  • @KatieK wall or USB should not make a difference.
    – sachleen
    Commented May 7, 2014 at 3:55

1 Answer 1


Yes, the RedBoard is preloaded with the blink sketch (or at least the two that I've purchased have been).

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