// Pin definitions
const int S0 = 2;
const int S1 = 3;
const int S2 = 4;
const int S3 = 5;
const int SIG_COM = 6;

void setup() {
  // Set the select pins as outputs
  pinMode(S0, OUTPUT);
  pinMode(S1, OUTPUT);
  pinMode(S2, OUTPUT);
  pinMode(S3, OUTPUT);
  
  // Set the common pin as output
  pinMode(SIG_COM, OUTPUT);

  // Initialize the serial monitor
  Serial.begin(9600);
}

void loop() {
  // Chase LEDs from right to left
  for (int channel = 0; channel < 16; channel++) {
    selectChannel(channel);
    digitalWrite(SIG_COM, HIGH);
    delay(35);
    digitalWrite(SIG_COM, LOW);
  }

  delay(10);

  // Chase LEDs from left to right
  for (int channel = 15; channel >= 0; channel--) {
    selectChannel(channel);
    digitalWrite(SIG_COM, HIGH);
    delay(35);
    digitalWrite(SIG_COM, LOW);
  }

}

void selectChannel(int channel) {
  digitalWrite(S0, bitRead(channel, 0));
  digitalWrite(S1, bitRead(channel, 1));
  digitalWrite(S2, bitRead(channel, 2));
  digitalWrite(S3, bitRead(channel, 3));
}