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ESP32 - Potentiometer Triggers Piezo Buzzer
This tutorial instructs you how to use ESP32 and the potentiometer to control the piezo buzzer. In detail:
- The ESP32 automatically turns the piezo buzzer on if the potentiometer's analog value is above a threshold
- The ESP32 automatically turns the piezo buzzer off if the potentiometer's analog value is under a threshold
We also learn how to convert the analog value to voltage and then use the voltage threshold to control the piezo buzzer:
- The ESP32 automatically turns the piezo buzzer on if the potentiometer's voltage is above a threshold.
- The ESP32 automatically turns the piezo buzzer off if the potentiometer's voltage is under a threshold.
We will use piezo buzzer to make sound and melody of song.
Hardware Used In This Tutorial
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Introduction to Piezo Buzzer and Potentiometer
We have specific tutorials about piezo buzzer and potentiometer. Each tutorial contains detailed information and step-by-step instructions about hardware pinout, working principle, wiring connection to ESP32, ESP32 code... Learn more about them at the following links:
Please note that this tutorial use 3-5V buzzer, but you can adapt it for 12v buzzer. you can learn about ESP32 - Buzzer tutorial
Wiring Diagram
This image is created using Fritzing. Click to enlarge image
If you're unfamiliar with how to supply power to the ESP32 and other components, you can find guidance in the following tutorial: How to Power ESP32.
ESP32 Code - Simple Sound - Analog Threshold
/*
* This ESP32 code is created by esp32io.com
*
* This ESP32 code is released in the public domain
*
* For more detail (instruction and wiring diagram), visit https://esp32io.com/tutorials/esp32-potentiometer-triggers-piezo-buzzer
*/
#define POTENTIOMETER_PIN 36 // ESP32 pin GPIO36 (ADC0) connected to Potentiometer pin
#define BUZZER_PIN 21 // ESP32 pin GPIO21 connected to Buzzer's pin
#define ANALOG_THRESHOLD 1000
void setup() {
// set the ADC attenuation to 11 dB (up to ~3.3V input)
analogSetAttenuation(ADC_11db);
pinMode(BUZZER_PIN, OUTPUT); // set ESP32 pin to output mode
}
void loop() {
int analogValue = analogRead(POTENTIOMETER_PIN); // read the input on analog pin
if (analogValue > ANALOG_THRESHOLD)
digitalWrite(BUZZER_PIN, HIGH); // turn on Piezo Buzzer
else
digitalWrite(BUZZER_PIN, LOW); // turn off Piezo Buzzer
}
Quick Instructions
- If this is the first time you use ESP32, see how to setup environment for ESP32 on Arduino IDE.
- Do the wiring as above image.
- Connect the ESP32 board to your PC via a micro USB cable
- Open Arduino IDE on your PC.
- Select the right ESP32 board (e.g. ESP32 Dev Module) and COM port.
- Copy the above code and paste it to Arduino IDE.
- Compile and upload code to ESP32 board by clicking Upload button on Arduino IDE
- Rotate the potentiometer
- Listen to piezo buzzer's sound
Line-by-line Code Explanation
The above ESP32 code contains line-by-line explanation. Please read the comments in the code!
ESP32 Code - Simple Sound - Voltage Threshold
The analog value read from the potentiometer is converted to voltage, and then the voltage is compared to a voltage threshold. If it exceeds the threshold, it triggers Piezo Buzzer
/*
* This ESP32 code is created by esp32io.com
*
* This ESP32 code is released in the public domain
*
* For more detail (instruction and wiring diagram), visit https://esp32io.com/tutorials/esp32-potentiometer-triggers-piezo-buzzer
*/
#define POTENTIOMETER_PIN 36 // ESP32 pin connected to Potentiometer pin
#define BUZZER_PIN 21 // ESP32 pin GPIO21 connected to Buzzer's pin
#define VOLTAGE_THRESHOLD 2.5 // Voltages
void setup() {
// set the ADC attenuation to 11 dB (up to ~3.3V input)
analogSetAttenuation(ADC_11db);
pinMode(BUZZER_PIN, OUTPUT); // set ESP32 pin to output mode
}
void loop() {
int analogValue = analogRead(POTENTIOMETER_PIN); // read the input on analog pin
float voltage = floatMap(analogValue, 0, 1023, 0, 5); // Rescale to potentiometer's voltage
if (voltage > VOLTAGE_THRESHOLD)
digitalWrite(BUZZER_PIN, HIGH); // turn on Piezo Buzzer
else
digitalWrite(BUZZER_PIN, LOW); // turn off Piezo Buzzer
}
float floatMap(float x, float in_min, float in_max, float out_min, float out_max) {
return (x - in_min) * (out_max - out_min) / (in_max - in_min) + out_min;
}
ESP32 Code - Melody - Voltage Threshold
/*
* This ESP32 code is created by esp32io.com
*
* This ESP32 code is released in the public domain
*
* For more detail (instruction and wiring diagram), visit https://esp32io.com/tutorials/esp32-potentiometer-triggers-piezo-buzzer
*/
#include "pitches.h"
#define POTENTIOMETER_PIN 36 // ESP32 pin GPIO36 (ADC0) connected to Potentiometer pin
#define BUZZER_PIN 21 // ESP32 pin GPIO21 connected to Buzzer's pin
#define VOLTAGE_THRESHOLD 2.5 // Voltages
// 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() {
// set the ADC attenuation to 11 dB (up to ~3.3V input)
analogSetAttenuation(ADC_11db);
}
void loop() {
int analogValue = analogRead(POTENTIOMETER_PIN); // read the input on analog pin
float voltage = floatMap(analogValue, 0, 1023, 0, 5); // Rescale to potentiometer's voltage
if (voltage > VOLTAGE_THRESHOLD)
playMelody(); // play a song
}
float floatMap(float x, float in_min, float in_max, float out_min, float out_max) {
return (x - in_min) * (out_max - out_min) / (in_max - in_min) + out_min;
}
void playMelody() {
// 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);
}
}
Quick Instructions
- Copy the above code and paste it to Arduino IDE.
- Create the pitches.h file On 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 file's name pitches.h and click OK button
- Copy the below code and paste it to the created pitches.h file.
- Compile and upload code to ESP32 board by clicking Upload button on Arduino IDE
- Rotate the potentiometer
- Listen to piezo buzzer's melody
- The ESP32 ADC is not perfectly accurate and might need calibration for correct results. Each ESP32 board can be a bit different, so you need to calibrate the ADC for each individual board.
- Calibration can be difficult, especially for beginners, and might not always give the exact results you want.
/*************************************************
* 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 code contains line-by-line explanation. Please read the comments in the code!
※ NOTE THAT:
This tutorial uses the analogRead() function to read values from an ADC (Analog-to-Digital Converter) connected to a potentiometer. The ESP32 ADC is good for projects that do NOT need high accuracy. However, for projects that need precise measurements, please note:
For projects that need high precision, consider using an external ADC (e.g ADS1115) with the ESP32 or using an Arduino, which has a more reliable ADC. If you still want to calibrate the ESP32 ADC, refer to ESP32 ADC Calibration Driver
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