Six-LED Level Meter with a Potentiometer

Lesson 14 · Reuse the potentiometer; build six outputs

Keep the potentiometer on A0. Add six LEDs to pins D2–D7, each with its own 220–330 Ω resistor and a common GND connection.

Map 0–1023 to levels 0–7

At level 0 all LEDs are off. As the knob turns, more LEDs illuminate. Level 7 means all six are on. Since there are eight numbered levels but only six LEDs, levels 6 and 7 both display all six on; print the number to distinguish them.

void setup() {
  pinMode(2, OUTPUT); pinMode(3, OUTPUT);
  pinMode(4, OUTPUT); pinMode(5, OUTPUT);
  pinMode(6, OUTPUT); pinMode(7, OUTPUT);
  Serial.begin(9600);
}
void loop() {
  int raw = analogRead(A0);
  int level = map(raw, 0, 1023, 0, 7);
  digitalWrite(2, level >= 1 ? HIGH : LOW);
  digitalWrite(3, level >= 2 ? HIGH : LOW);
  digitalWrite(4, level >= 3 ? HIGH : LOW);
  digitalWrite(5, level >= 4 ? HIGH : LOW);
  digitalWrite(6, level >= 5 ? HIGH : LOW);
  digitalWrite(7, level >= 6 ? HIGH : LOW);
  Serial.print("Raw: "); Serial.print(raw);
  Serial.print("  Level: "); Serial.println(level);
  delay(50);
}