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This example is for Wiring version 0024+. If you have a previous version, use the examples included with your software. If you see any errors or have comments, please let us know.

Blink an LED in a sequence by BARRAGAN http://barraganstudio.com
turns on and off an LED connected to a digital pin, with different intervals to create a sequence Note in the circuit the LED it has a positive (long leg) and a ground (short leg), if the LED doesn't turn ON, it might be it is inverted.

    int ledPin = 0;  // LED connected to the Wiring I/O board pin 0

    void setup()
    {
      pinMode(ledPin, OUTPUT);  // sets the digital pin as output
    }

    void loop()
    {
      digitalWrite(ledPin, HIGH);  // sets the LED on
      delay(100);                  // waits for 100ms
      digitalWrite(ledPin, LOW);   // sets the LED off
      delay(1000);                 // waits for a second
      digitalWrite(ledPin, HIGH);  // sets the LED on
      delay(100);                  // waits for 100ms
      digitalWrite(ledPin, LOW);   // sets the LED off
      delay(200);                  // waits for 200ms
    }