ESP32 C3 Super Mini - Motion Sensor - Piezo Buzzer
Build a simple motion alarm with an ESP32 C3 Super Mini, an HC-SR501 motion sensor and a piezo buzzer. When someone moves near the sensor, the buzzer makes a sound or plays a song.
In this tutorial, you'll learn:
- How to connect the HC-SR501 motion sensor and a piezo buzzer to ESP32 C3 Super Mini
- How to set the sensor's adjusters before you start
- How to make a sound when motion is detected, and stop the sound when motion stops
- How to play a melody when motion is detected
- How to create the pitches.h file in the Arduino IDE
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 Motion Sensor
The HC-SR501 is a motion sensor that detects moving people and animals, and the piezo buzzer is a small part that makes sound.
Key Features:
- HC-SR501 output: The OUTPUT pin is HIGH when motion is detected and LOW when there is no motion
- Piezo buzzer: Needs only one ESP32 C3 Super Mini GPIO pin
- Active buzzer: Makes a beep when its pin is HIGH, so it suits the simple sound code
- Passive buzzer: Plays different notes with tone(), so it suits the melody code
Technical Specifications:
- HC-SR501 power: 5V
- HC-SR501 OUTPUT signal: 3.3V when HIGH, safe for an ESP32 C3 Super Mini GPIO pin
- Detection range: Up to 7 meters, set by an adjuster on the sensor
- Active piezo buzzer voltage: 3V to 24V
- Piezo buzzer module voltage: 3.3V or 5V
Learn more about each part:
- 12V buzzer: This tutorial uses a buzzer at low voltage, but you can adapt it for a 12V buzzer. See the ESP32 C3 Super Mini - Buzzer tutorial
Wiring Diagram
Connect the motion sensor to GPIO5 and the buzzer to GPIO6 on the ESP32 C3 Super Mini.
- Note: Connect the HC-SR501 VCC pin to 5V. Its OUTPUT signal is 3.3V, so it is safe for GPIO5.
- Note: Check the polarity of the bare buzzer. The (+) pin has a longer leg or a + mark.
- Note: ESP32 C3 Super Mini GPIO pins are 3.3V only. Never feed 5V into a GPIO pin.
- 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
| HC-SR501 Pin | ESP32 C3 Super Mini Pin |
|---|---|
| VCC | 5V |
| GND | GND |
| OUTPUT | GPIO5 |
| Buzzer Pin | ESP32 C3 Super Mini Pin |
|---|---|
| Positive (+) | GPIO6 |
| Negative (-) | GND |
If you use a buzzer module, connect it like this:
| Module Pin | ESP32 C3 Super Mini Pin |
|---|---|
| GND | GND |
| VCC | 3.3V |
| I/O | GPIO6 |
Initial Setting
Set the adjusters and the jumper on the HC-SR501 before you run the code.
| Setting | Configuration |
|---|---|
| Detection Range Adjuster | Fully screw it in the clockwise direction. |
| Time Delay Adjuster | Fully screw it in the anti-clockwise direction. |
| Repeat Trigger Selector | Put the jumper as shown in the image below. |
ESP32 C3 Super Mini Code - Simple Sound
This code turns the buzzer on when motion starts and turns it off when motion stops.
What This Code Does:
- Reads the sensor: Checks the OUTPUT pin of the HC-SR501 on GPIO5 again and again
- Finds motion start: A change from LOW to HIGH turns the buzzer on through GPIO6
- Finds motion stop: A change from HIGH to LOW turns the buzzer off
- Reports events: Prints a message to the Serial Monitor at 115200 baud
/*
* 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-motion-sensor-piezo-buzzer
*/
#define MOTION_SENSOR_PIN 5 // The ESP32 C3 SuperMini pin GPIO5 connected to the OUTPUT pin of motion sensor
#define BUZZER_PIN 6 // The ESP32 C3 SuperMini pin GPIO6 connected to Buzzer's pin
int motionStateCurrent = LOW; // current state of motion sensor's pin
int motionStatePrevious = LOW; // previous state of motion sensor's pin
void setup() {
Serial.begin(115200); // initialize serial
pinMode(MOTION_SENSOR_PIN, INPUT); // set ESP32 C3 SuperMini pin to input mode
pinMode(BUZZER_PIN, OUTPUT); // set ESP32 C3 SuperMini pin to output mode
}
void loop() {
motionStatePrevious = motionStateCurrent; // store old state
motionStateCurrent = digitalRead(MOTION_SENSOR_PIN); // read new state
if (motionStatePrevious == LOW && motionStateCurrent == HIGH) { // pin state change: LOW -> HIGH
Serial.println("Motion detected!, making sound");
digitalWrite(BUZZER_PIN, HIGH); // turn on
} else if (motionStatePrevious == HIGH && motionStateCurrent == LOW) { // pin state change: HIGH -> LOW
Serial.println("Motion stopped!, stops making sound");
digitalWrite(BUZZER_PIN, LOW); // turn off
}
}
Detailed Instructions
Follow these bullets 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: Do the wiring as shown in the diagram above.
- Connect the board: Plug the ESP32 C3 Super Mini into your PC with a USB Type-C cable.
- Open the IDE: Open the Arduino IDE on your PC.
- 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 code above 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.
- Test it: Move your hand in front of the sensor.
- Listen: The piezo buzzer makes a sound.
- Pro Tip: No sound? Use an active buzzer for this code. A passive buzzer stays silent when its pin is only held HIGH.
Serial Monitor Output
You will see these messages when motion starts and stops:
8
Serial.println("Hello World!");
Message (Enter to send message to 'ESP32C3 Dev Module' on 'COM15')
New Line
9600 baud
Motion detected!, making sound
Motion stopped!, stops making sound
Motion detected!, making sound
Motion stopped!, stops making sound
Line-by-line Code Explanation
The ESP32 C3 Super Mini code above contains line-by-line explanation. Please read the comments in the code!
ESP32 C3 Super Mini Code - Melody
This code plays a melody on the buzzer whenever the sensor detects motion.
What This Code Does:
- Reads the sensor: Checks the OUTPUT pin of the HC-SR501 on GPIO5 in every loop
- Plays the song: Calls buzzer() when the pin is HIGH, using tone() on GPIO6
- Stores the song: Keeps the notes in melody[] and their lengths in noteDurations[]
- Stays quiet: Plays nothing while there is no motion
- Reports events: Prints a message to the Serial Monitor at 115200 baud
/*
* 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-motion-sensor-piezo-buzzer
*/
#include "pitches.h"
#define MOTION_SENSOR_PIN 5 // The ESP32 C3 SuperMini pin GPIO5 connected to the OUTPUT pin of motion sensor
#define BUZZER_PIN 6 // The ESP32 C3 SuperMini pin GPIO6 connected to Buzzer's pin
// 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() {
Serial.begin(115200); // initialize serial
pinMode(MOTION_SENSOR_PIN, INPUT); // set ESP32 C3 SuperMini pin to input mode
}
void loop() {
int motionState = digitalRead(MOTION_SENSOR_PIN); // read new state
if (motionState == HIGH) {
Serial.println("The motion is detected");
buzzer();
}
}
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 bullets 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 code above 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.
- Open the Serial Monitor: Set the baud rate to 115200.
- Test it: Move your hand in front of the sensor.
- Listen: The piezo buzzer plays the melody.
- Pro Tip: Use the passive buzzer module for this code. An active buzzer cannot play different notes.
/*************************************************
* 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
Serial Monitor Output
You will see this message each time the melody starts:
8
Serial.println("Hello World!");
Message (Enter to send message to 'ESP32C3 Dev Module' on 'COM15')
New Line
9600 baud
The motion is detected
The motion is detected
The motion is detected
Line-by-line Code Explanation
The ESP32 C3 Super Mini code above contains line-by-line explanation. Please read the comments in the code!
Application/Project Ideas
A motion sensor and a buzzer are a good start for many ESP32 C3 Super Mini projects.
- Door Alarm: Beep when someone walks through a door
- Welcome Chime: Play a short song when a guest enters a shop
- Pet Alert: Make a sound when your pet goes near the kitchen table
- Garage Warning: Beep when someone moves near your car
- Halloween Prop: Play a scary tune when someone comes close
Challenge Yourself
Try these small tasks to learn more about the ESP32 C3 Super Mini and the HC-SR501.
- Easy: Change the melody to another song with notes from pitches.h
- Easy: Make the buzzer beep on and off instead of staying on
- Medium: Add an LED on GPIO3 that turns on together with the buzzer
- Medium: Keep the buzzer on for 5 seconds after motion stops
- Advanced: Use the ezBuzzer library so the melody does not block other code