ESP32 C3 Super Mini - Ultrasonic Sensor - Piezo Buzzer
Build a simple distance alarm with the ESP32 C3 Super Mini, an ultrasonic sensor and a piezo buzzer. The buzzer sounds when an object comes close, and it stops when the object moves away.
In this tutorial, you'll learn:
- How the ESP32 C3 Super Mini turns the piezo buzzer on when an object is close to the ultrasonic sensor
- How the ESP32 C3 Super Mini turns the piezo buzzer off when the object is far from the ultrasonic sensor
- How to wire the HC-SR04 ultrasonic sensor and the piezo buzzer to the board
- How to play a simple sound when an object is closer than 50 cm
- How to play a melody instead of a simple sound
Hardware Preparation
Or you can buy the following kits:
| 1 | × | DIYables Sensor Kit (18 sensors/displays) |
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Additionally, some of these links are for products from our own brand, DIYables .
Additionally, some of these links are for products from our own brand, DIYables .
Overview of Piezo Buzzer and Ultrasonic Sensor
The ultrasonic sensor is a distance sensor that measures how far away an object is, and the piezo buzzer is a small part that makes sound.
Key Features:
- No touch needed: The ultrasonic sensor detects an object without touching it
- Simple sound output: The piezo buzzer needs only one GPIO pin
- Easy code: A few lines of code turn a distance reading into sound
Technical Specifications:
- Ultrasonic sensor voltage: 5V DC
- Measuring range: 2 cm to 400 cm
- Measuring angle: 15 degrees
- Buzzer voltage: This tutorial uses a 3-5V buzzer, and you can adapt it for a 12V buzzer
Learn more in our detailed tutorials (pinout, how it works, wiring and code):
- Piezo buzzer: ESP32 C3 Super Mini - Piezo Buzzer tutorial
- Ultrasonic sensor: ESP32 C3 Super Mini - Ultrasonic Sensor tutorial
- 12V buzzer: ESP32 C3 Super Mini - Buzzer tutorial
Pinout
Each part connects to the board with only a few pins.
- VCC (ultrasonic sensor): Connect to 5V power
- GND (ultrasonic sensor): Connect to ground (0V)
- TRIG (ultrasonic sensor): Receives the trigger pulse from the ESP32 C3 Super Mini
- ECHO (ultrasonic sensor): Sends a pulse back, and its length depends on the distance
- Positive (+) (piezo buzzer): Receives the control signal from the ESP32 C3 Super Mini
- Negative (-) (piezo buzzer): Connect to ground (0V)
Wiring Diagram
Connect the ultrasonic sensor and the piezo buzzer as shown below.
- Note: The ultrasonic sensor needs 5V power, so connect its VCC to the 5V pin.
- Note: Check the polarity of the bare buzzer. The (+) pin has a longer leg or a + mark.
The wiring diagram with power supply from USB cable:
This image is created using Fritzing. Click to enlarge image
The wiring diagram with power supply from 5V adapter:
This image is created using Fritzing. Click to enlarge image
| Ultrasonic Sensor Pin | ESP32 C3 Super Mini Pin |
|---|---|
| VCC | 5V |
| GND | GND |
| TRIG | GPIO1 |
| ECHO | GPIO10 |
| Piezo Buzzer Pin | ESP32 C3 Super Mini Pin |
|---|---|
| Positive (+) | GPIO7 |
| Negative (-) | GND |
ESP32 C3 Super Mini Code - Simple Sound
This ESP32 C3 Super Mini code turns the piezo buzzer on while an object is close to the ultrasonic sensor.
What This Code Does:
- Sends a 10-microsecond pulse to the TRIG pin on GPIO1
- Measures the echo pulse on the ECHO pin on GPIO10
- Calculates the distance in centimeters
- Turns the buzzer on GPIO7 on when the distance is below 50 cm, and off when it is not
- Prints the distance to the Serial Monitor every 500 milliseconds
/*
* This ESP32 C3 Super Mini code was developed by newbiely.com
*
* This ESP32 C3 Super Mini code is made available for public use without any restriction
*
* For comprehensive instructions and wiring diagrams, please visit:
* https://newbiely.com/tutorials/esp32-c3/esp32-c3-super-mini-ultrasonic-sensor-piezo-buzzer
*/
#define TRIG_PIN 1 // The ESP32 C3 SuperMini pin connected to Ultrasonic Sensor's TRIG pin
#define ECHO_PIN 10 // The ESP32 C3 SuperMini pin connected to Ultrasonic Sensor's ECHO pin
#define BUZZER_PIN 7 // The ESP32 C3 SuperMini pin connected to Piezo Buzzer's pin
#define DISTANCE_THRESHOLD 50 // centimeters
// variables will change:
float duration_us, distance_cm;
void setup() {
Serial.begin (115200); // initialize serial port
pinMode(TRIG_PIN, OUTPUT); // set ESP32 C3 SuperMini pin to output mode
pinMode(ECHO_PIN, INPUT); // set ESP32 C3 SuperMini pin to input mode
pinMode(BUZZER_PIN, OUTPUT); // set ESP32 C3 SuperMini pin to output mode
}
void loop() {
// generate 10-microsecond pulse to TRIG pin
digitalWrite(TRIG_PIN, HIGH);
delayMicroseconds(10);
digitalWrite(TRIG_PIN, LOW);
// measure duration of pulse from ECHO pin
duration_us = pulseIn(ECHO_PIN, HIGH);
// calculate the distance
distance_cm = 0.017 * duration_us;
if (distance_cm < DISTANCE_THRESHOLD)
digitalWrite(BUZZER_PIN, HIGH); // turn on Piezo Buzzer
else
digitalWrite(BUZZER_PIN, LOW); // turn off Piezo Buzzer
// print the value to Serial Monitor
Serial.print("distance: ");
Serial.print(distance_cm);
Serial.println(" cm");
delay(500);
}
Detailed Instructions
Follow these steps to run the simple sound example.
- New to ESP32 C3 Super Mini? Complete our Getting Started with ESP32 C3 Super Mini tutorial first to set up your development environment.
- Wire the parts: Follow the wiring diagram above.
- Connect the board: Plug the ESP32 C3 Super Mini into your computer with a USB Cable Type-C.
- Open the IDE: Launch the Arduino IDE on your computer.
- Select the board: Make sure ESP32 C3 Super Mini is selected in Tools > Board.
- Select the port: Pick the COM port of your board.
- Copy the code: Copy the above code and paste it into the Arduino IDE.
- Upload the code: Click the Upload button in the Arduino IDE.
- Open the Serial Monitor: Set the baud rate to 115200 to see the distance.
- Test it: Move your hand in front of the sensor.
- Listen: The piezo buzzer sounds when your hand is closer than 50 cm.
- Pro Tip: Hear nothing? Swap the two buzzer legs. A bare buzzer only works one way round.
Serial Monitor Output
The distance changes as you move your hand toward the sensor and away from it.
8
Serial.println("Hello World!");
Message (Enter to send message to 'ESP32C3 Dev Module' on 'COM15')
New Line
9600 baud
distance: 62.4 cm
distance: 48.7 cm
distance: 31.2 cm
distance: 54.9 cm
Line-by-line Code Explanation
The above ESP32 C3 Super Mini code contains line-by-line explanation. Please read the comments in the code!
ESP32 C3 Super Mini Code - Melody
This ESP32 C3 Super Mini code plays a melody when an object is close to the ultrasonic sensor.
What This Code Does:
- Measures the distance in the same way as the first example
- Reads note names such as NOTE_E5 from a pitches.h file
- Plays the whole melody on GPIO7 when the distance is below 50 cm
- Stays quiet when the object is far away
/*
* This ESP32 C3 Super Mini code was developed by newbiely.com
*
* This ESP32 C3 Super Mini code is made available for public use without any restriction
*
* For comprehensive instructions and wiring diagrams, please visit:
* https://newbiely.com/tutorials/esp32-c3/esp32-c3-super-mini-ultrasonic-sensor-piezo-buzzer
*/
#include "pitches.h"
#define TRIG_PIN 1 // The ESP32 C3 SuperMini pin connected to Ultrasonic Sensor's TRIG pin
#define ECHO_PIN 10 // The ESP32 C3 SuperMini pin connected to Ultrasonic Sensor's ECHO pin
#define BUZZER_PIN 7 // The ESP32 C3 SuperMini pin connected to Piezo Buzzer's pin
#define DISTANCE_THRESHOLD 50 // centimeters
// variables will change:
float duration_us, distance_cm;
// notes in the melody:
int melody[] = {
NOTE_E5, NOTE_E5, NOTE_E5,
NOTE_E5, NOTE_E5, NOTE_E5,
NOTE_E5, NOTE_G5, NOTE_C5, NOTE_D5,
NOTE_E5,
NOTE_F5, NOTE_F5, NOTE_F5, NOTE_F5,
NOTE_F5, NOTE_E5, NOTE_E5, NOTE_E5, NOTE_E5,
NOTE_E5, NOTE_D5, NOTE_D5, NOTE_E5,
NOTE_D5, NOTE_G5
};
// note durations: 4 = quarter note, 8 = eighth note, etc, also called tempo:
int noteDurations[] = {
8, 8, 4,
8, 8, 4,
8, 8, 8, 8,
2,
8, 8, 8, 8,
8, 8, 8, 16, 16,
8, 8, 8, 8,
4, 4
};
void setup() {
pinMode(TRIG_PIN, OUTPUT); // set ESP32 C3 SuperMini pin to output mode
pinMode(ECHO_PIN, INPUT); // set ESP32 C3 SuperMini pin to input mode
}
void loop() {
// generate 10-microsecond pulse to TRIG pin
digitalWrite(TRIG_PIN, HIGH);
delayMicroseconds(10);
digitalWrite(TRIG_PIN, LOW);
// measure duration of pulse from ECHO pin
duration_us = pulseIn(ECHO_PIN, HIGH);
// calculate the distance
distance_cm = 0.017 * duration_us;
if (distance_cm < DISTANCE_THRESHOLD)
buzzer(); // play a song
delay(500);
}
void buzzer() {
// iterate over the notes of the melody:
int size = sizeof(noteDurations) / sizeof(int);
for (int thisNote = 0; thisNote < size; thisNote++) {
// to calculate the note duration, take one second divided by the note type.
//e.g. quarter note = 1000 / 4, eighth note = 1000/8, etc.
int noteDuration = 1000 / noteDurations[thisNote];
tone(BUZZER_PIN, melody[thisNote], noteDuration);
// to distinguish the notes, set a minimum time between them.
// the note's duration + 30% seems to work well:
int pauseBetweenNotes = noteDuration * 1.30;
delay(pauseBetweenNotes);
// stop the tone playing:
noTone(BUZZER_PIN);
}
}
Detailed Instructions
Follow these steps to run the melody example.
- New to ESP32 C3 Super Mini? Complete our Getting Started with ESP32 C3 Super Mini tutorial first to set up your development environment.
- Select the board: Make sure ESP32 C3 Super Mini is selected in Tools > Board.
- Copy the code: Copy the above code and paste it into the Arduino IDE.
- Create the pitches.h file in the Arduino IDE by:
- Either click on the button just below the serial monitor icon and choose New Tab, or use Ctrl+Shift+N keys.
- Give the file the name pitches.h and click the OK button.
- Copy the code below and paste it into the new pitches.h file.
- Upload the code: Click the Upload button in the Arduino IDE.
- Test it: Move your hand in front of the sensor.
- Listen: The piezo buzzer plays the melody.
- Serial Monitor: This sketch prints nothing. If you add your own Serial.print() lines, use Serial.begin(115200) and set the baud rate to 115200.
- Pro Tip: A passive buzzer module plays the melody best, because it follows each note.
/*************************************************
* Public Constants
*************************************************/
#define NOTE_B0 31
#define NOTE_C1 33
#define NOTE_CS1 35
#define NOTE_D1 37
#define NOTE_DS1 39
#define NOTE_E1 41
#define NOTE_F1 44
#define NOTE_FS1 46
#define NOTE_G1 49
#define NOTE_GS1 52
#define NOTE_A1 55
#define NOTE_AS1 58
#define NOTE_B1 62
#define NOTE_C2 65
#define NOTE_CS2 69
#define NOTE_D2 73
#define NOTE_DS2 78
#define NOTE_E2 82
#define NOTE_F2 87
#define NOTE_FS2 93
#define NOTE_G2 98
#define NOTE_GS2 104
#define NOTE_A2 110
#define NOTE_AS2 117
#define NOTE_B2 123
#define NOTE_C3 131
#define NOTE_CS3 139
#define NOTE_D3 147
#define NOTE_DS3 156
#define NOTE_E3 165
#define NOTE_F3 175
#define NOTE_FS3 185
#define NOTE_G3 196
#define NOTE_GS3 208
#define NOTE_A3 220
#define NOTE_AS3 233
#define NOTE_B3 247
#define NOTE_C4 262
#define NOTE_CS4 277
#define NOTE_D4 294
#define NOTE_DS4 311
#define NOTE_E4 330
#define NOTE_F4 349
#define NOTE_FS4 370
#define NOTE_G4 392
#define NOTE_GS4 415
#define NOTE_A4 440
#define NOTE_AS4 466
#define NOTE_B4 494
#define NOTE_C5 523
#define NOTE_CS5 554
#define NOTE_D5 587
#define NOTE_DS5 622
#define NOTE_E5 659
#define NOTE_F5 698
#define NOTE_FS5 740
#define NOTE_G5 784
#define NOTE_GS5 831
#define NOTE_A5 880
#define NOTE_AS5 932
#define NOTE_B5 988
#define NOTE_C6 1047
#define NOTE_CS6 1109
#define NOTE_D6 1175
#define NOTE_DS6 1245
#define NOTE_E6 1319
#define NOTE_F6 1397
#define NOTE_FS6 1480
#define NOTE_G6 1568
#define NOTE_GS6 1661
#define NOTE_A6 1760
#define NOTE_AS6 1865
#define NOTE_B6 1976
#define NOTE_C7 2093
#define NOTE_CS7 2217
#define NOTE_D7 2349
#define NOTE_DS7 2489
#define NOTE_E7 2637
#define NOTE_F7 2794
#define NOTE_FS7 2960
#define NOTE_G7 3136
#define NOTE_GS7 3322
#define NOTE_A7 3520
#define NOTE_AS7 3729
#define NOTE_B7 3951
#define NOTE_C8 4186
#define NOTE_CS8 4435
#define NOTE_D8 4699
#define NOTE_DS8 4978
Line-by-line Code Explanation
The above ESP32 C3 Super Mini code contains line-by-line explanation. Please read the comments in the code!
Application and Project Ideas
Here are simple ways to use the ESP32 C3 Super Mini with an ultrasonic sensor and a piezo buzzer.
- Parking helper: Beep when a car gets close to the garage wall
- Doorway alert: Sound when someone walks through a door
- Desk distance reminder: Beep when you sit too close to the screen
- Robot warning: Sound when a small robot gets close to an obstacle
- Welcome melody: Play a song when a person walks up to a shop counter
Challenge Yourself
Ready for more? Try these challenges with your ESP32 C3 Super Mini.
- Easy: Change DISTANCE_THRESHOLD from 50 cm to 20 cm
- Easy: Replace the melody with another song from your own notes
- Medium: Beep faster as the object gets closer
- Medium: Add an LED that lights up together with the buzzer
- Advanced: Use the ezBuzzer library so the code keeps measuring the distance during the melody