/*
  Blink
  Turns on an LED on for one second, then off for one second, repeatedly.

  Most Arduinos have an on-board LED you can control. On the Uno and
  Leonardo, it is attached to digital pin 13. If you're unsure what
  pin the on-board LED is connected to on your Arduino model, check
  the documentation at http://www.arduino.cc

  This example code is in the public domain.

  modified 8 May 2014
  by Scott Fitzgerald
 */

const int ledmin = 8;
const int ledmax = 13;
const int leds = ledmax - ledmin;

int Delay = 500/leds;

// the setup function runs once when you press reset or power the board
void setup() {
  // initialize digital pin 13 as an output.
  for (int i = ledmin; i <= ledmax; i++)
  {
    pinMode(i, OUTPUT);
  }
}

// the loop function runs over and over again forever
void loop() {
  up();
  down();
}

void up() {
  for (int i = ledmax; i >= ledmin; i--)
  {
    digitalWrite(i, HIGH);
    delay(Delay);
  }
}

void down() {
  for (int i = ledmax; i >= ledmin; i--)
  {
    digitalWrite(i, LOW);
    delay(Delay);
  }
}