Multiplexer (Array)

const int channel[] = {

  8, 9, 10, 11};

// the output pin channel (mux's input):

const int outputPin = 6;

void setup() {

  // set up all pins as output:

  for (int thisPin = 6; thisPin < 12; thisPin++) {

    pinMode(thisPin, OUTPUT);

  }

}

void loop() {

  // iterate over the 16 channels of the multiplexer:

  for (int thisChannel = 0; thisChannel < 16; thisChannel++) {

    // set the channel pins based on the channel you want:

    muxWrite(thisChannel);

    // fade the current channel up:

    for (int brightness = 0; brightness < 256; brightness++) {

      analogWrite(outputPin, brightness);

      delay(5);

    }

  }

}

void muxWrite(int whichChannel) {

  // iterate over the number of pins you're using:

  for (int thisPin = 0; thisPin < 4; thisPin++) {

    // calculate the state of this pin based on 

    // its bit value in whichChannel:

    int pinState = bitRead(whichChannel, thisPin);

    // turn the pin on or off:

    digitalWrite(channel[thisPin],pinState);

  }

}