ESP32 - Siren

In this tutorial, we are going to learn how to program ESP32 to control a siren to produce a warning sound and/or light.

Hardware Used In This Tutorial

1×ESP-WROOM-32 Dev Module
1×USB Cable Type-C
1×12V Alarm Siren Horn
1×12V Power Adapter
1×(Optional) DC Power Jack
1×Jumper Wires
1×(Recommended) ESP32 Screw Terminal Adapter

Or you can buy the following sensor kits:

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

Depending on the manufacturer, a siren can produce either a loud sound or a warning light, making it suitable for an alarm system. It is also available in several operating voltages. This tutorial will use a 12V siren, and other voltages will be similar.


ESP32 12V siren Pinout

12V siren usually has two pins:

  • Negative (-) pin (black): needs to be connected to GND of DC power supply
  • Positive (+) pin (red): needs to be connected to 12V of DC power supply

How to Control a Siren

If 12V siren is powered by 12V power supply, it make sound and/or warning light. To control a 12V siren, we need to use a relay in between ESP32 and 12V siren. ESP32 can control the 12V siren via the relay. If you do not know about relay (pinout, how it works, how to program ...), learn about relay in the ESP32 - Relay tutorial

Wiring Diagram

ESP32 12V siren 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

The below code repeatedly turns the 12V siren ON in three seconds and OFF in five seconds,

/* * This ESP32 code is created by * * This ESP32 code is released in the public domain * * For more detail (instruction and wiring diagram), visit */ #define RELAY_PIN 16 // ESP32 pin GPIO16 that controls the siren via relay // the setup function runs once when you press reset or power the board void setup() { // initialize digital pin as an output. pinMode(RELAY_PIN, OUTPUT); } void loop() { digitalWrite(RELAY_PIN, HIGH); delay(3000); digitalWrite(RELAY_PIN, LOW); delay(5000); }

Quick Instructions

  • If this is the first time you use ESP32, see how to setup environment for ESP32 on Arduino IDE
  • Connect ESP32 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 ESP32
  • Check out the siren's state

Code Explanation

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

Video Tutorial

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