Arduino - Sound Sensor - LED

In this tutorial, we'll explore how to utilize the sound sensor for LED control. Specifically, we'll delve into two exciting applications:

Sound switch: When sound is detected (e.g knock), the Arduino toggles the LED, turning it on if it's off, and off if it's on.
Sound-activated LED: Upon detecting sound, the Arduino turns on the LED for a specific period of time.

Hardware Required

1	×	Arduino UNO or Genuino UNO
1	×	USB 2.0 cable type A/B (for USB-A PC)
1	×	USB 2.0 cable type C/B (for USB-C PC)
1	×	Sound Sensor
1	×	LED
1	×	220 ohm resistor
1	×	Breadboard
1	×	Jumper Wires
1	×	(Recommended) Screw Terminal Block Shield for Arduino Uno
1	×	(Recommended) Breadboard Shield For Arduino Uno
1	×	(Recommended) Enclosure For Arduino Uno

Or you can buy the following sensor kits:

1	×	DIYables Sensor Kit (30 sensors/displays)
1	×	DIYables Sensor Kit (18 sensors/displays)

Disclosure: Some links in this section are Amazon affiliate links. If you make a purchase through these links, we may earn a commission at no extra cost to you.
Additionally, some links direct to products from our own brand, DIYables.

About LED and Sound Sensor

If you do not know about led and sound sensor (pinout, how it works, how to program ...), learn about them in the following tutorials:

Wiring Diagram

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Arduino Code - Sound Switch toggles LED

The below code toggles the state of LED each time the sound is detected.

/* * Created by ArduinoGetStarted.com * * This example code is in the public domain * * Tutorial page: https://arduinogetstarted.com/tutorials/arduino-sound-sensor-led */ #define SENSOR_PIN A0 // Arduino pin connected to sound sensor's pin #define LED_PIN 7 // Arduino pin connected to LED's pin int lastSoundState; // the previous state of sound sensor int currentSoundState; // the current state of sound sensor int ledState = LOW; // the current state of LED void setup() { Serial.begin(9600); // initialize serial pinMode(SENSOR_PIN, INPUT); // set arduino pin to input mode pinMode(LED_PIN, OUTPUT); // set arduino pin to output mode currentSoundState = digitalRead(SENSOR_PIN); } void loop() { lastSoundState = currentSoundState; // save the last state currentSoundState = digitalRead(SENSOR_PIN); // read new state if (lastSoundState == HIGH && currentSoundState == LOW) { // state change: HIGH -> LOW Serial.println("The sound has been detected"); // toggle state of LED ledState = !ledState; // control LED arccoding to the toggled state digitalWrite(LED_PIN, ledState); } }

Quick Steps

Connect Arduino to PC via USB cable
Open Arduino IDE, select the right board and port
Copy the above code and open with Arduino IDE
Click Upload button on Arduino IDE to upload code to Arduino

Clap your hand in front of the sound sensor
See the change of LED's state

Code Explanation

Read the line-by-line explanation in comment lines of source code!

Arduino Code - Sound-activated LED for a period of time

The below code turns on LED for a period of time when the sound is detected. After the period of time, LED is turned off.

/* * Created by ArduinoGetStarted.com * * This example code is in the public domain * * Tutorial page: https://arduinogetstarted.com/tutorials/arduino-sound-sensor-led */ #define SENSOR_PIN A0 // Arduino pin connected to sound sensor's pin #define LED_PIN 7 // Arduino pin connected to LED's pin #define TIME_PERIOD 5000 // in milliseconds int lastSoundState; // the previous state of sound sensor int currentSoundState; // the current state of sound sensor void setup() { Serial.begin(9600); // initialize serial pinMode(SENSOR_PIN, INPUT); // set arduino pin to input mode pinMode(LED_PIN, OUTPUT); // set arduino pin to output mode currentSoundState = digitalRead(SENSOR_PIN); } void loop() { lastSoundState = currentSoundState; // save the last state currentSoundState = digitalRead(SENSOR_PIN); // read new state if (lastSoundState == HIGH && currentSoundState == LOW) { // state change: HIGH -> LOW Serial.println("The sound has been detected"); // turn on LED digitalWrite(LED_PIN, HIGH); delay(TIME_PERIOD); // turn off LED digitalWrite(LED_PIN, LOW); } }

Please take note that the previous code utilizes the delay() function, which is straightforward to understand. However, when additional code is added, the delay() function can cause blocking issues during the delay period. To overcome this, the following code implements a non-blocking approach by utilizing the ezLED library. The ezLED library, working behind the scenes, utilizes the millis() function instead of delay to prevent blocking.

/* * Created by ArduinoGetStarted.com * * This example code is in the public domain * * Tutorial page: https://arduinogetstarted.com/tutorials/arduino-sound-sensor-led */ #include <ezLED.h> // ezLED library #define SENSOR_PIN A0 // Arduino pin connected to sound sensor's pin #define LED_PIN 7 // Arduino pin connected to LED's pin #define TIME_PERIOD 5000 // in milliseconds ezLED led(LED_PIN); // create a LED object that attach to pin LED_PIN int lastSoundState; // the previous state of sound sensor int currentSoundState; // the current state of sound sensor void setup() { Serial.begin(9600); // initialize serial pinMode(SENSOR_PIN, INPUT); // set arduino pin to input mode currentSoundState = digitalRead(SENSOR_PIN); } void loop() { led.loop(); // MUST call the led.loop() function in loop() lastSoundState = currentSoundState; // save the last state currentSoundState = digitalRead(SENSOR_PIN); // read new state if (lastSoundState == HIGH && currentSoundState == LOW) { // state change: HIGH -> LOW Serial.println("The sound has been detected"); led.turnON(); // turn on immediately led.turnOFF(TIME_PERIOD); // turn off after TIME_PERIOD } }

Quick Steps

Connect Arduino to PC via USB cable
Open Arduino IDE, select the right board and port
Navigate to the Libraries icon on the left bar of the Arduino IDE.
Search “ezLED”, then find the led library by ArduinoGetStarted
Click Install button to install ezLED library.

Copy the above code and open with Arduino IDE
Click Upload button on Arduino IDE to upload code to Arduino

Clap your hand in front of the sound sensor
See the change of LED's state

Video Tutorial

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The Best Arduino Starter Kit

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Arduino - Sound Sensor - LED

Hardware Required

About LED and Sound Sensor

Wiring Diagram

Arduino Code - Sound Switch toggles LED

Quick Steps

Code Explanation

Arduino Code - Sound-activated LED for a period of time

Quick Steps

Video Tutorial

The Best Arduino Starter Kit

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