#include <NewPing.h>

#define TRIGGER_PIN  4  // Arduino pin tied to trigger pin on the ultrasonic sensor.
#define ECHO_PIN     3  // Arduino pin tied to echo pin on the ultrasonic sensor.
#define MAX_DISTANCE 500 // Maximum distance we want to ping for (in centimeters). Maximum sensor distance is rated at 400-500cm.
#define led_green 8
#define led_blue 9
#define led_red 10

NewPing sonar(TRIGGER_PIN, ECHO_PIN, MAX_DISTANCE); // NewPing setup of pins and maximum distance.

int dist_cm;

void setup() {
  Serial.begin(115200); // Open serial monitor at 115200 baud to see ping results.
  pinMode(led_green, OUTPUT);
  pinMode(led_blue, OUTPUT);
  pinMode(led_red, OUTPUT);
}

void loop() {
  delay(50);                     // Wait 50ms between pings (about 20 pings/sec). 29ms should be the shortest delay between pings.
  dist_cm=sonar.ping_cm();
  Serial.print("Ping: ");
  Serial.print(dist_cm); // Send ping, get distance in cm and print result (0 = outside set distance range)
  Serial.println("cm");

  if (dist_cm>=100){
    digitalWrite(led_green, HIGH);
    digitalWrite(led_blue, LOW);
    digitalWrite(led_red, HIGH);
  } else{
    if (dist_cm<100 && dist_cm>=50){
      digitalWrite(led_green, LOW);
      digitalWrite(led_blue, HIGH);
      digitalWrite(led_red, HIGH);
    } else {
      if (dist_cm<50 && dist_cm>=30){
          digitalWrite(led_green, HIGH);
          digitalWrite(led_blue, HIGH);
          digitalWrite(led_red, LOW);
      } else{
        digitalWrite(led_green, HIGH);
        digitalWrite(led_blue, HIGH);
        digitalWrite(led_red, LOW);
        delay(500);
        digitalWrite(led_red, HIGH);
        delay(500);
      }
    }
  }
}