PROJECT 12 : SMART SIREN ALERT SYSTEM

1 min read

0:00 1:27

This project aims to design and implement an Arduino-based smart siren alarm system. Using the Arduino microcontroller, you will control a siren or buzzer to produce a loud, wailing sound for alarms or warnings. You can use this system in security setups or emergency alert systems. Additionally, the system uses LEDs for visual alerts, offering a multi-sensory warning. You will also integrate a push button that triggers different alarms based on user interaction.

Materials to use

Circuit diagram

Connect the buzzer to digital pin 12 on the control board, the button on pins 3 and 9, and the LEDs to pins 4 through 11.

Figure: Schematic diagram

Figure: Components used to make connection on the board

Arduino Code

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 // numbers  of LEDs pins
const int led1 = 4;
const int led2 = 5;
const int led3 = 6;
const int led4 = 7;
const int led5 = 8;
const int led6 = 9;
const int led7 = 10;
const int led8 = 11;
int laststate=0;// read LEDs state
const int buzzer =12; // use pin 12 t0o control buzzer
const int button1 = 3;// use pin 3 to control  button
int buttonState1 = 0; // read button state value
void setup(){
// set the output pin modes
pinMode(buzzer, OUTPUT);
pinMode(button1, INPUT);
pinMode(led7, OUTPUT);
pinMode(led6, OUTPUT);
pinMode(led5, OUTPUT);
pinMode(led1, OUTPUT);
pinMode(led2, OUTPUT);
pinMode(led3 OUTPUT);
pinMode(led4 OUTPUT);
pinMode(led8, OUTPUT);
}
void loop(){
   buttonState1 = digitalRead(button1);// read the buttons value
 if (buttonState1 == HIGH)// if the button turned on{
 for(int i=2;i<=11;i++) {
    digitalWrite(i,HIGH);
    tone(buzzer,i,3000);// all LEDs will turn on with the buzzer/div>
    delay(500);// stop the program after five milliseconds
    digitalWrite(i,LOW);// the program will turn OFF
}
}
 laststate = digitalRead(button1);// read the buttons value
if (laststate ==HIGH &&buttonState1 ==HIGH){
 for(int(int i=2;i<=9;i++){
    digitalWrite(i,HIGH);
    tone(buzzer,i,500);
    delay(10);
    digitalWrite(i,LOW);
}
}
}
After verifying and uploading the code, pressing the button will trigger the buzzer to change its sound, while the LEDs switch colors, acting as an alarm system.
ResultThis project controls a sequence of 8 LEDs and a buzzer based on the state of a button connected to pin 3. Here’s what you can expect as the visible output and the program’s behavior:
Initial State: All LEDs (led1 to led8) and the buzzer are OFF.
When you press the button:
 All LEDs (led1 to led8) turn ON sequentially. Each LED lights up in order (led1 → led2 → … → led8) for 500 milliseconds before turning OFF.
Activates the buzzer: The buzzer produces a tone with varying frequencies corresponding to the current LED pin (e.g., frequency 4 Hz for led1). The tone plays for 3 seconds (3000 ms) before moving to the next LED.
This loop repeats for all LEDs, creating a pattern where each LED turns ON/OFF with a buzzer tone.
When you release the button: 
 LEDs (led1 to led8) light up sequentially.
The buzzer produces a short tone (500 ms) at varying frequencies, corresponding to the LED pin. LEDs turn ON for 10 ms and then OFF as the loop progresses.
Behavior Summary
Pressing the button activates:
A slower sequence: LEDs light up one at a time for 500 ms, with a long buzzer tone (3 seconds) for each LED.
Releasing the button activates:
A faster sequence: LEDs light up one at a time for 10 ms, with a short buzzer tone (500 ms) for each LED.

Updated on October 13, 2026

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