//Interface 2 led with arduino
int led1 = 13;
int led2 = 8;
void setup()
{
  pinMode(led1, OUTPUT);
  pinMode(led2, OUTPUT);
}
void loop()
{
  digitalWrite(led1, HIGH);
  digitalWrite(led2, LOW);
  delay(1000);
  digitalWrite(led1, LOW);
  digitalWrite(led2, HIGH);
  delay(1000);
}