ultrasonic

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

const byte Echo = 2;//kaki ultrasonik
const byte Trig = 3;//kaki ultrasonik
long duration;
int distance;
int jarak;
String line1, line2;
unsigned long old_time;
const unsigned long tinggi_tabung = 15000;
float baca_tinggi_tabung;

void setup() {
   Serial.begin(9600);
   lcd.autoAddress();
   lcd.begin();
   pinMode(Echo, INPUT);
   pinMode(Trig, OUTPUT);
}

void loop() {
   if( millis() - old_time >= 250 ){
    get_data();
    old_time = millis();
   }
}
void baca_sensor(int trigPin, int echoPin){
  digitalWrite(trigPin, LOW);
  delayMicroseconds(2);
  digitalWrite(trigPin, HIGH);
  delayMicroseconds(10);
  digitalWrite(trigPin,LOW);
  duration = pulseIn(echoPin, HIGH);
  distance = duration * 0.034/2;
}
void get_data(){
  baca_sensor(Trig,Echo);
  jarak = distance;
  baca_tinggi_tabung = tinggi_tabung - (float)jarak/100;
  line1 = String("Jarak: ") + jarak + " cm";
  line2 = String("Tinggi: ") + String(baca_tinggi_tabung,2) + " m";
  lcd.clear();
  lcd.setCursor(0,0);
  lcd.print(line1);
  lcd.setCursor(0,1);
  lcd.print(line2);
}