Example 3.1

gistfile1.txt

// example 3.1

void setup()
{ 
  pinMode (2, OUTPUT); // set pin 2 as an output pin
} 

void loop()
{ 
  for (int i = 1; i<=20; i++) // loop 20 times
  { 
    digitalWrite (2, HIGH); // turn on pin2 for 1 second, then off for one second
    delay (1000);
    digitalWrite (2, LOW);
    delay (1000);
  }
  delay (2000);
}