ESP32-C3 Buzzer Simulator: Wiring, Code and a Live Circuit
This is a passive piezo buzzer wired to an ESP32-C3 DevKitM-1, 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: GPIO 5 to the buzzer’s plus side and GND to the other. No library is needed.
- 3.3 V logic
- No library: tone()
- Signal on GPIO 5
- Passive piezo
Wiring the Buzzer to the ESP32-C3
Every connection in the circuit above, with the board’s own pin names.
| Buzzer pin | ESP32-C3 pin | Why |
|---|---|---|
| Pin 1 | GPIO 5 | 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 runs straight from a 3.3 V pin; it is quieter than at 5 V. On an ESP32-C3 DevKitM-1 tone() makes the square wave in hardware (LEDC), so the core is free while a note plays. A magnetic buzzer draws more than a pin should give, so drive one through a transistor.
Pins to leave alone on the ESP32-C3
GPIO 8 carries the onboard LED and GPIO 9 is the BOOT button, and both are also the default I2C pins. GPIO 2, 8 and 9 are strapping pins, and only GPIO 0 to 4 can read an analog voltage.
On a real bench
The ESP32-C3 DevKitM-1 is small enough to sit on one breadboard with room for the Buzzer beside it. Its USB port goes through a USB-to-serial chip; the cheaper SuperMini boards use the C3’s own USB, where Serial needs USB CDC on boot turned on in the IDE.
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 = 5; // GPIO 5
// C, E, G, C: an arpeggio, a quarter second a note.
const int NOTES[] = {523, 659, 784, 1047};
void setup() {
Serial.begin(115200);
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(115200) opens the serial monitor. Serial is UART0, at 115200 baud in this sketch.
Common mistakes with the Buzzer on the ESP32-C3
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 GPIO 8 or 9
GPIO 8 drives the onboard LED and GPIO 9 is the BOOT button, and both are strapping pins read at power-on. Wired to the buzzer, either can stop a real board from booting. GPIO 4 and GPIO 5 are free of both.
Questions and answers
Can I simulate a buzzer with an ESP32-C3 DevKitM-1?
Yes. The circuit at the top of this page is an ESP32-C3 DevKitM-1 with a piezo buzzer, running in your browser on a simulated ESP32-C3 (RISC-V). 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.