//22.11.4562 - Muhammad Guido Augusta

#include <LiquidCrystal_I2C.h>
LiquidCrystal_I2C lcd(0x27 ,16, 2);

const int ledRed = 10;
const int ledYellow = 11;
const int ledGreen = 12;

long bacaJarak (int triggerPin, int echoPin){
  pinMode(triggerPin, OUTPUT);
  digitalWrite(triggerPin, LOW);
  digitalWrite(triggerPin, HIGH);
  delayMicroseconds(10);
  digitalWrite(triggerPin, LOW);
  pinMode(echoPin, INPUT);
  return pulseIn(echoPin, HIGH);
}

void setup() {
  // put your setup code here, to run once:
  Serial.begin(9600);

  lcd.init();
  lcd.backlight();
  lcd.begin(16,2);
}

void loop() {
  // put your main code here, to run repeatedly:
  int cm = 0; //reset cm ke e
  cm = (0.03446 * bacaJarak (7,8))/2;
  lcd.setCursor(0, 0);
  lcd.print("jarak: ");
  lcd.setCursor(7, 0);
  lcd.print(cm);
  lcd.setCursor(10, 0);
  lcd.print(" CM");

  if (cm > 15) {
    digitalWrite(ledRed, LOW);
    digitalWrite(ledYellow, LOW);
    digitalWrite(ledGreen, HIGH);
  } else if (cm >= 5 && cm <= 15) {
    digitalWrite(ledRed, LOW);
    digitalWrite(ledYellow, HIGH);
    digitalWrite(ledGreen, LOW);
  } else {
    digitalWrite(ledRed, HIGH);
    digitalWrite(ledYellow, LOW);
    digitalWrite(ledGreen, LOW);
  }

  Serial.print(cm);
  Serial.println("cm");

  delay(500);
  lcd.clear();
}