// Professor: Christian Bodington E. 
  // www.conexionelectronica.com

  // Exercise # 1-3: Handling I/O ports.

void setup() {

  // Initialize the digital pins as an output.

  DDRD = B11111111;  // sets Arduino pins 0 to 7 as outputs

  }

  // the loop routine runs over and over again forever:

void loop() {

  for (int led=0; led <=7; led++){
    digitalWrite(led, HIGH);		// Turn the led On.
    delay(50);						// Wait	for 50 milliseconds
    digitalWrite(led, LOW);			// Turn the led Off.
    delay(50);
  }
  
 }