Mux eight on an Arduino Uno

// Mux eight: three knobs read on one analog pin through a 74HC4051.
//
// Wiring, multiplexer to board:
//   S0 (pin 11) -> pin 2, S1 (pin 10) -> pin 3, S2 (pin 9) -> pin 4
//   Z  (pin 3)  -> A0
//   E (pin 6), VEE (pin 7) and GND (pin 8) to GND, VCC (pin 16) to 5 V
//   the knobs' wipers on Y0, Y1 and Y2
//
// The address on S0 to S2 joins one of the eight channels to Z through an
// analog switch, so A0 reads whichever knob is selected. The switch has some
// 70 ohm of resistance and A0 has a little capacitance, so the sketch waits
// a moment after changing the address before it reads.

const uint8_t ADDRESS[3] = {2, 3, 4};

int readChannel(uint8_t channel) {
  for (uint8_t bit = 0; bit < 3; 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 < 3; bit++) pinMode(ADDRESS[bit], OUTPUT);
  Serial.println("Mux eight: channels 0, 1 and 2");
}

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