Driving Multiple LEDs

/*
  SparkFun Inventor's Kit
  Example sketch 04

  MULTIPLE LEDs

  Make six LEDs dance. Dance LEDs, dance!


  This sketch was written by SparkFun Electronics,
  with lots of help from the Arduino community.
  This code is completely free for any use.
  Visit http://learn.sparkfun.com/products/2 for SIK information.
  Visit http://www.arduino.cc to learn about the Arduino.
*/


// To keep track of all the LED pins, we'll use an "array".
// An array lets you store a group of variables, and refer to them
// by their position, or "index". Here we're creating an array of
// six integers, and initializing them to a set of values:
int ledPins[] = {4, 5, 6, 7, 8, 9};


void setup()
{
  //create a local variable to store the index of whcih pin we want to control
  int index;


  // For the for() loop below, these are the three statements:

  //   1. index = 0;    Before starting, make index = 0.
  //   2. index <= 5;   If index is less or equal to 5, run the following code
  //   3. index++   Putting "++" after a variable means "add one to it".

  // When the test in statement 2 is finally false, the sketch
  // will continue.

  // This for() loop will make index = 0, then run the pinMode()
  // statement within the brackets. It will then do the same thing
  // for index = 2, index = 3, etc. all the way to index = 5.

  for (index = 0; index <= 5; index++)
  {
    pinMode(ledPins[index], OUTPUT);
  }
}


void loop()
{
  // This loop() calls functions that we've written further below.
  // We've disabled some of these by commenting them out (putting
  // "//" in front of them). To try different LED displays, remove
  // the "//" in front of the ones you'd like to run, and add "//"
  // in front of those you don't to comment out (and disable) those
  // lines.

  // Light up all the LEDs in turn
  oneAfterAnotherNoLoop();

  // Same as oneAfterAnotherNoLoop, but less typing
  //oneAfterAnotherLoop();

  // Turn on one LED at a time, scrolling down the line
  //oneOnAtATime();

  // Light the LEDs middle to the edges
  //pingPong();

  // Chase lights like you see on signs
  //marquee();

  // Blink LEDs randomly
  //randomLED();
}


/*
  oneAfterAnotherNoLoop()
  This function will light one LED, delay for delayTime, then light
  the next LED, and repeat until all the LEDs are on. It will then
  turn them off in the reverse order.
*/

void oneAfterAnotherNoLoop()
{
  // time (milliseconds) to pause between LEDs
  int delayTime = 100;


  // turn all the LEDs on:

  digitalWrite(ledPins[0], HIGH);  //Turns on LED #0 (pin 4)
  delay(delayTime);                //wait delayTime milliseconds
  digitalWrite(ledPins[1], HIGH);  //Turns on LED #1 (pin 5)
  delay(delayTime);                //wait delayTime milliseconds
  digitalWrite(ledPins[2], HIGH);  //Turns on LED #2 (pin 6)
  delay(delayTime);                //wait delayTime milliseconds
  digitalWrite(ledPins[3], HIGH);  //Turns on LED #3 (pin 7)
  delay(delayTime);                //wait delayTime milliseconds
  digitalWrite(ledPins[4], HIGH);  //Turns on LED #4 (pin 8)
  delay(delayTime);                //wait delayTime milliseconds
  digitalWrite(ledPins[5], HIGH);  //Turns on LED #5 (pin 9)
  delay(delayTime);                //wait delayTime milliseconds

  // turn all the LEDs off:

  digitalWrite(ledPins[5], LOW);   //Turn off LED #5 (pin 9)
  delay(delayTime);                //wait delayTime milliseconds
  digitalWrite(ledPins[4], LOW);   //Turn off LED #4 (pin 8)
  delay(delayTime);                //wait delayTime milliseconds
  digitalWrite(ledPins[3], LOW);   //Turn off LED #3 (pin 7)
  delay(delayTime);                //wait delayTime milliseconds
  digitalWrite(ledPins[2], LOW);   //Turn off LED #2 (pin 6)
  delay(delayTime);                //wait delayTime milliseconds
  digitalWrite(ledPins[1], LOW);   //Turn off LED #1 (pin 5)
  delay(delayTime);                //wait delayTime milliseconds
  digitalWrite(ledPins[0], LOW);   //Turn off LED #0 (pin 4)
  delay(delayTime);                //wait delayTime milliseconds
}


/*
  oneAfterAnotherLoop()

  This function does exactly the same thing as oneAfterAnotherNoLoop(),
  but it takes advantage of for() loops and the array to do it with
  much less typing.
*/

void oneAfterAnotherLoop()
{
  int index;
  int delayTime = 100; // milliseconds to pause between LEDs
  // make this smaller for faster switching

  // Turn all the LEDs on:

  // This for() loop will step index from 0 to 5
  // (putting "++" after a variable means add one to it)
  // and will then use digitalWrite() to turn that LED on.

  for (index = 0; index <= 5; index++)
  {
    digitalWrite(ledPins[index], HIGH);
    delay(delayTime);
  }

  // Turn all the LEDs off:

  // This for() loop will step index from 5 to 0
  // (putting "--" after a variable means subtract one from it)
  // and will then use digitalWrite() to turn that LED off.

  for (index = 5; index >= 0; index--)
  {
    digitalWrite(ledPins[index], LOW);
    delay(delayTime);
  }
}


/*
  oneOnAtATime()

  This function will step through the LEDs,
  lighting only one at at time.
*/

void oneOnAtATime()
{
  int index;
  int delayTime = 100; // milliseconds to pause between LEDs
  // make this smaller for faster switching

  // step through the LEDs, from 0 to 5

  for (index = 0; index <= 5; index++)
  {
    digitalWrite(ledPins[index], HIGH);  // turn LED on
    delay(delayTime);                    // pause to slow down
    digitalWrite(ledPins[index], LOW);   // turn LED off
  }
}


/*
  pingPong()

  This function will step through the LEDs,
  lighting one at at time in both directions.
*/

void pingPong()
{
  int index;
  int delayTime = 100; // milliseconds to pause between LEDs
  // make this smaller for faster switching

  // step through the LEDs, from 0 to 5

  for (index = 0; index <= 5; index++)
  {
    digitalWrite(ledPins[index], HIGH);  // turn LED on
    delay(delayTime);                    // pause to slow down
    digitalWrite(ledPins[index], LOW);   // turn LED off
  }

  // step through the LEDs, from 5 to 0

  for (index = 5; index >= 0; index--)
  {
    digitalWrite(ledPins[index], HIGH);  // turn LED on
    delay(delayTime);                    // pause to slow down
    digitalWrite(ledPins[index], LOW);   // turn LED off
  }
}


/*
  marquee()

  This function will mimic "chase lights" like those around signs.
*/

void marquee()
{
  int index;
  int delayTime = 200; // milliseconds to pause between LEDs
  // Make this smaller for faster switching

  // Step through the first four LEDs
  // (We'll light up one in the lower 3 and one in the upper 3)

  for (index = 0; index <= 2; index++) // Step from 0 to 3
  {
    digitalWrite(ledPins[index], HIGH);    // Turn a LED on
    digitalWrite(ledPins[index + 3], HIGH); // Skip four, and turn that LED on
    delay(delayTime);                      // Pause to slow down the sequence
    digitalWrite(ledPins[index], LOW);     // Turn the LED off
    digitalWrite(ledPins[index + 3], LOW); // Skip four, and turn that LED off
  }
}


/*
  randomLED()

  This function will turn on random LEDs. Can you modify it so it
  also lights them for random times?
*/

void randomLED()
{
  int index;
  int delayTime;

  // The random() function will return a semi-random number each
  // time it is called. See http://arduino.cc/en/Reference/Random
  // for tips on how to make random() even more random.

  index = random(5);    // pick a random number between 0 and 5
  delayTime = 100;

  digitalWrite(ledPins[index], HIGH);  // turn LED on
  delay(delayTime);                    // pause to slow down
  digitalWrite(ledPins[index], LOW);   // turn LED off
}