Mux knobs on an Arduino Uno

// Mux knobs: a CD74HC4067 reads three potentiometers on one analog pin.
//
//   CD74HC4067   S0 S1 S2 S3 -> pins 2 3 4 5   EN -> GND   COM -> A0
//                VCC -> 5 V   GND -> GND
//   pots         wipers on channels 0, 5 and 15, ends across 5 V and GND
//
// The 4067 is sixteen switches with one common pin, and the four address
// lines pick which one is closed. To read channel n the sketch puts n on S0
// to S3, waits a moment for the switch and the ADC's input to settle, and
// reads A0. Sixteen knobs, four digital pins and one analog pin.
//
// Turn the three knobs.

const uint8_t ADDRESS[4] = {2, 3, 4, 5};
const uint8_t CHANNELS[3] = {0, 5, 15};

int readChannel(uint8_t channel) {
  for (uint8_t bit = 0; bit < 4; bit++) {
    digitalWrite(ADDRESS[bit], (channel >> bit) & 1 ? HIGH : LOW);
  }
  delayMicroseconds(50);
  return analogRead(A0);
}

void setup() {
  Serial.begin(9600);
  for (uint8_t bit = 0; bit < 4; bit++) pinMode(ADDRESS[bit], OUTPUT);
  Serial.println("Mux knobs: channels 0, 5 and 15");
}

void loop() {
  for (uint8_t i = 0; i < 3; i++) {
    Serial.print("ch");
    Serial.print(CHANNELS[i]);
    Serial.print(" ");
    Serial.print(readChannel(CHANNELS[i]));
    Serial.print(i < 2 ? "  " : "\n");
  }
  delay(300);
}