This project is perfect for Arduino beginners who want to get hands-on with real circuits and LED control. Follow these steps to build your very own police-style LED flasher with Red, White, and Blue LEDs.

Step 1: Gather All Components

You’ll need the following parts:

Arduino Uno

Breadboard

Red LED

White LED

Blue LED

Jumper wires (male-to-male)

3x Resistors (220–330 ohms)

USB cable to upload code from your computer

 Step 2: Connect the LEDs

Let’s wire each LED to its respective pin on the Arduino.

Red LED → Pin 13

White LED → Pin 12

Blue LED → Pin 11

Connect the cathode (short leg) of all LEDs to the GND rail on the breadboard

Connect GND rail to GND on Arduino

Place one resistor in series with each LED (on the anode side)

 Tip: Always use resistors to avoid damaging the LEDs.

Step 3: Understand the Code in Detail

This project uses a simple Arduino sketch to turn LEDs ON and OFF in a pattern that simulates police lights. Let’s break down the code and explain each part so you know exactly what’s happening and how to tweak it.

✅ The Setup Block

void setup() {

  pinMode(13, OUTPUT);

  pinMode(12, OUTPUT);

  pinMode(11, OUTPUT);

}

This runs once when your Arduino powers up.

pinMode(pin, OUTPUT); tells the Arduino that pins 13, 12, and 11 will control outputs — in this case, LEDs.

🧠 You can change the pins here if you’re using different ones for your LEDs.

The Loop Block

void loop() {

  digitalWrite(13, HIGH); // RED ON

  digitalWrite(12, HIGH); // WHITE ON

  digitalWrite(11, LOW); // BLUE OFF

  delay(80);

digitalWrite(pin, HIGH); turns the LED ON

digitalWrite(pin, LOW); turns the LED OFF

delay(80); pauses the code for 80 milliseconds before moving to the next step

In this first part:

RED and WHITE LEDs turn ON

BLUE is OFF

The pattern stays for 80ms

digitalWrite(13, LOW);

  digitalWrite(12, HIGH);

  digitalWrite(11, LOW);

  delay(80);

Now:

Only WHITE LED remains ON

RED and BLUE are OFF

Another short pause

This creates a flashing “pulse” with emphasis on the WHITE LED.

—

digitalWrite(13, HIGH);

  digitalWrite(12, HIGH);

  digitalWrite(11, LOW);

  delay(0);

RED and WHITE are ON again, no delay this time (makes it look like a flicker)

—

digitalWrite(13, LOW);

  digitalWrite(12, HIGH);

  digitalWrite(11, HIGH);

  delay(80);

WHITE and BLUE ON

RED OFF

This changes the light effect, simulating the opposite end of a strobe.

—

digitalWrite(13, LOW);

  digitalWrite(12, HIGH);

  digitalWrite(11, LOW);

  delay(80);

And again, we flash WHITE only.

—

digitalWrite(13, LOW);

  digitalWrite(12, HIGH);

  digitalWrite(11, HIGH);

  delay(0);

}

Ends the loop with WHITE and BLUE ON again — but instantly moves back to the start.

🛠️ How to Change the Flash Pattern

Want a slower flash? Just increase the delay values. For example:

delay(300); // 300ms = slower

Want each LED to blink one-by-one? Try this simple loop:

void loop() {

  digitalWrite(13, HIGH); delay(200);

  digitalWrite(13, LOW);

  digitalWrite(12, HIGH); delay(200);

  digitalWrite(12, LOW);

  digitalWrite(11, HIGH); delay(200);

  digitalWrite(11, LOW);

}

🧪 Experiment: Try using different delays for each LED to create rhythmic or random police-like effects.

—

🧠 Bonus Tip: Use millis() Instead of delay()

If you want more advanced control without freezing the program, you can replace delay() with millis() for non-blocking flashing patterns. But for now, delay() is easiest for beginners.

💻 Step 4: Upload the Code

Open the Arduino IDE on your computer, connect the Arduino Uno, And Select the Valid Com Port  and upload the code below:

void setup() {

  pinMode(13, OUTPUT);

  pinMode(12, OUTPUT);

  pinMode(11, OUTPUT);

}

void loop() {

  digitalWrite(13, HIGH);

  digitalWrite(12, HIGH);

  digitalWrite(11, LOW);

  delay(80);

  digitalWrite(13, LOW);

  digitalWrite(12, HIGH);

  digitalWrite(11, LOW);

  delay(80);

  digitalWrite(13, HIGH);

  digitalWrite(12, HIGH);

  digitalWrite(11, LOW);

  delay(0);

  digitalWrite(13, LOW);

  digitalWrite(12, HIGH);

  digitalWrite(11, HIGH);

  delay(80);

  digitalWrite(13, LOW);

  digitalWrite(12, HIGH);

  digitalWrite(11, LOW);

  delay(80);

  digitalWrite(13, LOW);

  digitalWrite(12, HIGH);

  digitalWrite(11, HIGH);

  delay(0);

}

—

▶️ Step 5: Power it Up!

Plug in the Arduino using a USB cable

Once the code uploads, the LEDs will start blinking in a repeating police-style pattern

🎯 What You’ve Learned

✅ How to control LEDs using digital pins

✅ Using pinMode() and digitalWrite() functions

✅ Creating timed patterns with delay()

✅ Building a functional breadboard circuit