This example is for Wiring version 0027+. 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 by BARRAGAN http://barraganstudio.com
turns on and off an LED connected to digital pin 0, with intervals of 1 second (1000 milliseconds) 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 digital pin 0
void setup()
{
pinMode(ledPin, OUTPUT); // set ledPin pin as output
}
void loop()
{
digitalWrite(ledPin, HIGH); // set the LED on
delay(1000); // wait for a second
digitalWrite(ledPin, LOW); // set the LED off
delay(1000); // wait for a second
}