Play a tune with an Arduino buzzer — tone(), arrays and Ode to Joy

#What you will build

A small round buzzer that plays the first line of "Ode to Joy" by Beethoven — fifteen notes — then pauses for a second and a half and plays it again. The serial monitor prints the frequency of each note as it plays.

Buzzers like this beep in microwaves, alarm clocks, washing machines and toys. The same code idea — a list of notes and a list of lengths — is how ringtones and old video-game music were made.

#How it works

A passive piezo buzzer contains a thin disc that bends a tiny bit every time the voltage on it changes. One change makes one click. Many clicks a second make a tone — and the faster the clicks, the higher the note. More in the passive buzzer explained.

The Arduino function tone(pin, frequency) does the switching for you: it flips the pin HIGH and LOW exactly that many times per second, in the background, while your program carries on.

A musical note is just a frequency, measured in hertz (Hz), cycles per second:

The tune's timing: one beat is 300 ms. Each note sounds for its beats minus 30 ms, so repeated notes (E E, G G) are heard as two separate notes, not one long one. The whole line is 16 beats = 4.8 seconds.

#The wiring

Only two wires, and no resistor: a piezo buzzer draws almost no steady current.

1. Push the buzzer into the breadboard with its + leg in 15b and its other leg in 18b.
2. Jumper wire from pin 8 → 15a.
3. Jumper wire from 18a → GND.

#The code, line by line

const int BUZZER = 8;
// "Ode to Joy" (Beethoven): E E F G G F E D C C D E E D D
const int NOTES[] = { 330, 330, 349, 392, 392, 349, 330, 294, 262, 262, 294, 330, 330, 294, 294 };
const int BEATS[] = { 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 2 };
const int COUNT = 15;
const int BEAT = 300; // ms

void setup() {
  Serial.begin(9600);
}

void loop() {
  for (int i = 0; i < COUNT; i++) {
    int ms = BEATS[i] * BEAT;
    tone(BUZZER, NOTES[i], ms - 30);
    Serial.println(NOTES[i]);
    delay(ms);
  }
  delay(1500);
}

• const int NOTES[] = { 330, … }; is an array: one name for a whole list of numbers. NOTES[0] is the first (330), NOTES[14] the last. Counting starts at 0.
• BEATS[] is a second list, the same length: how many beats each note lasts. Only the last note is 2 beats long.
• COUNT = 15 is how many notes there are. BEAT = 300 is the length of one beat in milliseconds — the tempo.
• for (int i = 0; i < COUNT; i++) repeats the block 15 times, with i going 0, 1, 2 … 14. i++ means "add one to i".
• int ms = BEATS[i] * BEAT; works out this note's length: 300 ms, or 600 ms for the last one.
• tone(BUZZER, NOTES[i], ms - 30) starts the note and stops it by itself after ms − 30 milliseconds.
• delay(ms) waits for the whole note, including the 30 ms of silence, before the next one. (tone() does not wait by itself.)
• delay(1500) after the loop: a pause before the tune starts again.

#Common mistakes

• Only clicks, or one fixed beep. You have an active buzzer. Use a passive one for tunes.
• All the notes blur into one. Without the - 30, repeated notes join up. Keep a short gap between notes.
• The tune plays too fast and sounds wrong. delay(ms) is missing, so every tone() replaces the last one immediately.
• Silence. The buzzer is on a different pin than the code says (8), or both legs are in the same strip. In the 3D lab, also check that sound is on in the toolbar.

#Try these challenges

1. Change the tempo: try BEAT = 200 (faster) and BEAT = 450 (slower).
2. Play it one octave higher by doubling the frequency: tone(BUZZER, NOTES[i] * 2, ms - 30);.
3. Write your own tune: change both arrays and COUNT. Keep the two arrays the same length!
4. In the 3D lab, turn sound on in the toolbar, press Run, and watch the frequencies scroll by in the serial monitor.

#Check yourself

#Questions people ask

#What is the difference between an active and a passive buzzer?

An active buzzer has a built-in oscillator: give it 5 V and it beeps at one fixed pitch. A passive buzzer needs a changing signal, which tone() provides — so it can play any note.

#Does a buzzer need a resistor on Arduino?

A small passive piezo buzzer, like this one, does not: it draws almost no steady current. Some people add 100 Ω to make it a little quieter.

#Can I play two notes at once with tone()?

No. tone() works on one pin at a time; starting a new tone stops the old one. For chords you need extra hardware or a special library.

#What are the frequencies of musical notes for Arduino?

Middle C is 262 Hz, then D 294, E 330, F 349, G 392, A 440, B 494 and the next C 523. Double them for the octave above, halve them for the octave below.

#What's next

The buzzer plays a song by itself. Now put you in charge: eight buttons become keys in the Arduino mini piano.

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Last updated 2026-10-29