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Arduino UNO-Based Smart Traffic Light System with RFID Ambulance Priority and I2C LCD Display

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Circuit Documentation

Summary

This circuit is designed to manage a traffic light system with priority given to ambulances detected via an RFID reader. The system uses an Arduino UNO microcontroller to control three traffic lights and an I2C LCD display to provide status updates. The RFID reader detects authorized ambulance tags and adjusts the traffic lights accordingly to prioritize the ambulance's route.

Component List

  1. Arduino UNO

    • Description: A microcontroller board based on the ATmega328P.
    • Pins: UNUSED, IOREF, Reset, 3.3V, 5V, GND, Vin, A0, A1, A2, A3, A4, A5, SCL, SDA, AREF, D13, D12, D11, D10, D9, D8, D7, D6, D5, D4, D3, D2, D1, D0

  2. 16x2 I2C LCD

    • Description: A 16x2 character LCD display with I2C interface.
    • Pins: GND, VCC, SDA, SCL

  3. Traffic Light (North)

    • Description: A traffic light with three LEDs (Green, Yellow, Red) and a ground pin.
    • Pins: Green, Yellow, Red, GND

  4. Traffic Light (South)

    • Description: A traffic light with three LEDs (Green, Yellow, Red) and a ground pin.
    • Pins: Green, Yellow, Red, GND

  5. Traffic Light (East)

    • Description: A traffic light with three LEDs (Green, Yellow, Red) and a ground pin.
    • Pins: Green, Yellow, Red, GND

  6. RFID-RC522

    • Description: An RFID reader module.
    • Pins: VCC (3.3V), RST, GND, IRQ, MISO, MOSI, SCK, SDA

Wiring Details

Arduino UNO

16x2 I2C LCD

Traffic Light (North)

Traffic Light (South)

Traffic Light (East)

RFID-RC522

Documented Code

#include <SPI.h>
#include <MFRC522.h>
#include <Wire.h>
#include <LiquidCrystal_I2C.h>

// Pin assignments for RFID
#define SS_PIN A1
#define RST_PIN A0
MFRC522 mfrc522(SS_PIN, RST_PIN);

// Pin assignments for traffic lights (LEDs)
const int redN = 2, yellowN = 3, greenN = 4;    // North traffic light
const int redS = 5, yellowS = 6, greenS = 7;   // South traffic light
const int redE = 8, yellowE = 9, greenE = 10;  // East traffic light

// Define ambulance RFID tag UID
byte authorizedUID[4] = {0x43, 0x89, 0x6C, 0xFA};

// Initialize I2C LCD (address 0x27, 16 columns, 2 rows)
LiquidCrystal_I2C lcd(0x27, 16, 2);

void setup() {
  // Initialize traffic lights
  pinMode(redN, OUTPUT);
  pinMode(yellowN, OUTPUT);
  pinMode(greenN, OUTPUT);
  pinMode(redS, OUTPUT);
  pinMode(yellowS, OUTPUT);
  pinMode(greenS, OUTPUT);
  pinMode(redE, OUTPUT);
  pinMode(yellowE, OUTPUT);
  pinMode(greenE, OUTPUT);

  // Initialize Serial Monitor, RFID reader, and LCD
  Serial.begin(9600);
  SPI.begin();
  mfrc522.PCD_Init();

  lcd.init(); // Initialize the LCD
  lcd.backlight(); // Turn on the backlight
  lcd.setCursor(0, 0);
  lcd.print("Place RFID tag...");
}

void loop() {
  // Check if RFID card is present
  if (mfrc522.PICC_IsNewCardPresent() && mfrc522.PICC_ReadCardSerial()) {
    if (isAmbulanceDetected()) {
      handleAmbulancePriority();
    }
    mfrc522.PICC_HaltA(); // Stop reading the card
  }

  // Normal traffic light sequence
  normalTrafficSequence();
}

// Function to check if the scanned tag matches the ambulance tag
bool isAmbulanceDetected() {
  for (byte i = 0; i < 4; i++) {
    if (mfrc522.uid.uidByte[i] != authorizedUID[i]) {
      return false;
    }
  }
  return true;
}

// Function to handle ambulance priority
void handleAmbulancePriority() {
  Serial.println("Ambulance detected! Prioritizing North road...");
  lcd.clear();
  lcd.setCursor(0, 0);
  lcd.print("Ambulance Detected");
  lcd.setCursor(0, 1);
  lcd.print("North: Green");

  // Set all lights to red
  digitalWrite(yellowN, LOW);
  digitalWrite(yellowS, LOW);
  digitalWrite(yellowE, LOW);
  digitalWrite(greenN, LOW);
  digitalWrite(greenS, LOW);
  digitalWrite(greenE, LOW);
  digitalWrite(redN, HIGH);
  digitalWrite(redS, HIGH);
  digitalWrite(redE, HIGH);
  delay(500);
  digitalWrite(redN, LOW);
  digitalWrite(redS, LOW);
  digitalWrite(redE, LOW);
  delay(500);
  digitalWrite(redN, HIGH);
  digitalWrite(redS, HIGH);
  digitalWrite(redE, HIGH);
  delay(500);
  digitalWrite(redN, LOW);
  digitalWrite(redS, LOW);
  digitalWrite(redE, LOW);
  delay(500);
  digitalWrite(redN, HIGH);
  digitalWrite(redS, HIGH);
  digitalWrite(redE, HIGH);
  delay(500);
  digitalWrite(redN, LOW);
  digitalWrite(redS, LOW);
  digitalWrite(redE, LOW);
  

  // Set North green light
  digitalWrite(redN, LOW);
  digitalWrite(greenN, HIGH);

  // Keep North light green for 10 seconds
  delay(10000);

  // Set North light back to red
  digitalWrite(greenN, LOW);
  digitalWrite(redN, HIGH);

  lcd.clear();
}

// Function for normal traffic light sequence
void normalTrafficSequence() {
  lcd.clear();
  lcd