Arduino Uno Buzzer Simulator: Wiring, Code and a Live Circuit
This is a passive piezo buzzer wired to an Arduino Uno, playing a four-note arpeggio with tone() live in your browser. The simulated piezo measures the frequency on its legs, so a wrong note is a wrong number.
Two wires: pin 8 to the buzzer’s plus side and GND to the other. No library is needed.
- 5 V logic
- No library: tone()
- Signal on pin 8
- Passive piezo
Wiring the Buzzer to the Arduino Uno
Every connection in the circuit above, with the board’s own pin names.
| Buzzer pin | Arduino Uno pin | Why |
|---|---|---|
| Pin 1 | pin 8 | tone() puts a square wave at the note’s frequency on this pin. |
| Pin 2 | GND | Ground. A passive piezo has no polarity. |
A small passive piezo draws a few milliamps and runs straight from the pin. On the ATmega328P, tone() takes Timer2, so PWM on pins 3 and 11 pauses while a note plays.
Pins to leave alone on the Arduino Uno
Pins 0 and 1 are the USB serial port on a real Uno, so anything wired there fights the upload and the serial monitor. Pin 13 carries the onboard LED.
On a real bench
On a real bench the Uno stands beside the breadboard: the Buzzer goes into the breadboard and male-to-male jumpers run from the Uno’s female headers to its rows. Power the Uno from USB while you build, and unplug it before you move a wire.
The code
The sketch the circuit above runs. Open it in the editor, change a line and press Run: it compiles in your browser.
const int BUZZER_PIN = 8; // pin 8
// C, E, G, C: an arpeggio, a quarter second a note.
const int NOTES[] = {523, 659, 784, 1047};
void setup() {
Serial.begin(9600);
Serial.println("Playing");
}
void loop() {
for (int i = 0; i < 4; i++) {
tone(BUZZER_PIN, NOTES[i], 200); // returns at once; the note plays on
delay(250);
}
noTone(BUZZER_PIN);
Serial.println("Again");
delay(500);
}
tone(pin, frequency, duration) starts a square wave and returns at once; the note stops on its own after duration milliseconds. That is why the loop still needs delay(250): without it all four notes would start within microseconds of each other.
The frequencies are the notes of a C major arpeggio, from 523 Hz (C5) to 1047 Hz (C6). #include "pitches.h" gives names like NOTE_C5 for the same numbers.
Serial.begin(9600) opens the serial monitor. Serial goes over the USB cable, and the serial monitor in the editor reads it at whatever baud rate the sketch sets.
Common mistakes with the Buzzer on the Arduino Uno
An active buzzer
An active buzzer has its own oscillator and beeps at one pitch whenever it has power, so tone() cannot change its note. For melodies you need a passive one; the two look the same, but the active kind usually has a sticker on top.
No delay between notes
tone() does not wait for the note to finish. Call it twice in a row and only the second note plays. Wait at least as long as the note, as the sketch does.
Using pins 0 and 1
Pins 0 and 1 carry the USB serial port on a real Uno. the buzzer wired there fights every upload and every Serial.print(). Start at pin 2.
Questions and answers
Can I simulate a buzzer with an Arduino Uno?
Yes. The circuit at the top of this page is an Arduino Uno with a piezo buzzer, running in your browser on a simulated ATmega328P. The simulated piezo reports the frequency it is driven at, and the editor’s scope can show the square wave on the pin. Press Run it in the editor to change the wiring or the code; it is free and needs no account.
Can I play two notes at once?
Not with tone(): it drives one pin at a time. Two buzzers on two pins with your own timing can, or a DFPlayer module for recorded sound.
How do I make it louder?
Drive the piezo from two pins in opposite phase, or through a transistor from a higher voltage. A magnetic buzzer is louder but needs the transistor.
Where do I find the note frequencies?
#include "pitches.h" in the editor gives NOTE_ names from NOTE_B0 (31 Hz) to NOTE_DS8 (4978 Hz), the same list the Arduino toneMelody example uses.
Build your own Buzzer project
Open this circuit in the editor, change the wiring or the code, and keep your version in a free account.