#include <NewPing.h>

#define TRIGGER_PIN PB1
#define ECHO_PIN PB0
#define GREEN_LED PB5
#define YELLOW_LED PB3
#define RED_LED PB2
#define BUZZER PB2

#define MAX_DISTANCE 20000 // Maximum distance for detecting car presence

NewPing sonar(TRIGGER_PIN, ECHO_PIN, MAX_DISTANCE);

void setup() {
  pinMode(GREEN_LED, OUTPUT);
  pinMode(YELLOW_LED, OUTPUT);
  pinMode(RED_LED, OUTPUT);
  pinMode(BUZZER, OUTPUT);
} 

void loop() {
  delay(50);
  unsigned int distance = sonar.ping_cm();

  if (distance < 120) {
    digitalWrite(GREEN_LED, HIGH);
  } else {
    digitalWrite(GREEN_LED, LOW);
  }

  if (distance < 80) {
    digitalWrite(YELLOW_LED, HIGH);
  } else {
    digitalWrite(YELLOW_LED, LOW);
  }

  if (distance < 40) {
    digitalWrite(RED_LED, HIGH);
    digitalWrite(BUZZER, HIGH);
  } else {
    digitalWrite(RED_LED, LOW);
    digitalWrite(BUZZER, LOW);
  }
}