Complete Grade Crossing System

// Grade Crossing System
#include <Servo.h>
#include <DFRobotDFPlayerMini.h>
#include <SoftwareSerial.h>

SoftwareSerial mp3Serial(10, 11);
DFRobotDFPlayerMini mp3;
Servo gate;

const int SENSOR_APPROACH = 2;
const int SENSOR_EXIT = 3;
const int LED1 = 4, LED2 = 5;

void setup() {
  mp3Serial.begin(9600);
  mp3.begin(mp3Serial);
  gate.attach(9);
  gate.write(90); // Gate up
}

void activateCrossing() {
  mp3.play(1); // Bell sound
  gate.write(0); // Lower gate
  // Flash LEDs...
}