int mode = 1;

int total = 2; // maximum 8

int potPIN = A0; // analog pin
int potVAL = 0;

int ledPIN = 3; // digital pin
int ledVAL = LOW;

int muxPIN[] = {10,11,12}; // digital pin
String MUX = "MUX ";

int k = 0;

void writeMux(int x) {
  for (int i = 0; i < 3; i++) {
    if (bitRead(x,i) == 1) {
      digitalWrite(muxPIN[i],HIGH);
    } else {
      digitalWrite(muxPIN[i],LOW);
    }
  }
}

void setup() {
  Serial.begin(9600); // for serial monitor
  pinMode(potPIN, INPUT);
  pinMode(ledPIN, OUTPUT);
  for (int i = 0; i < 3; i++) {
    pinMode(muxPIN[i], OUTPUT);
  }

}

void loop() {
  // MODE 0
  if (mode == 0) {
    potVAL = analogRead(potPIN);
    Serial.println(potVAL);
    delay(100);
  }
  // MODE 1
  else if (mode == 1) {
    while (k < total) {
      writeMux(k);
      digitalWrite(ledPIN, HIGH);
      potVAL = analogRead(potPIN);
      String mOut = MUX + k;
      Serial.println(mOut);
      Serial.print("\t");
      Serial.println(potVAL);
      delay(1000);

      if (k == (total - 1)) {
        k = 0;
      }
      else {
        k++;
      }
      digitalWrite(ledPIN,LOW);
    }
  }
  // UNUSED DEFAULT CASE
  else {

  }
}