#include <LiquidCrystal.h>
const int trigpin = 3;
const int echopin = 4;
const int gledpin = 12;
const int rledpin = 13;
LiquidCrystal lcd{7,6,5,4,9,8};
const int buzzerpin = 10;

void setup() {
  // put your setup code here, to run once:

  lcd.begin(16,2);
  pinMode(trigpin, OUTPUT);
  pinMode(echopin, INPUT);
  pinMode(gledpin, OUTPUT);
  pinMode(rledpin, OUTPUT);
  pinMode(buzzerpin, OUTPUT);
  noTone(buzzerpin);
}

void loop() {
  long duration;
  int distance;

	digitalWrite(trigpin, LOW);
	delayMicroseconds(2);
	// Sets the trigger pin to HIGH state for 10 microseconds
	digitalWrite(trigpin, HIGH);
	delayMicroseconds(10);
	digitalWrite(trigpin, LOW);
  
  duration = pulseIn(echopin,HIGH);
  distance = duration / 29 /2;
  
  lcd.clear();
  lcd.setCursor(0,0);
  lcd.print("distance = ");
  lcd.print(distance);
  lcd.print(" cm");

  if(distance < 100){
    int tonefreq = map(distance, 0, 20, 200, 2000);
    tone(buzzerpin,tonefreq);
    digitalWrite(rledpin, HIGH);
    digitalWrite(gledpin, LOW);
    lcd.setCursor(0,1);
    lcd.print("STOP!");
  }
  else{
    noTone(buzzerpin);
    digitalWrite(rledpin, LOW);
    digitalWrite(gledpin, HIGH);
    lcd.setCursor(0,1);
    lcd.print("Move");
  }
  delay(100);
}