int trig=13,echo=12,buzzerPin=1;
#include <LiquidCrystal_I2C.h>
LiquidCrystal_I2C lcd(0x27, 16, 2);
void setup() {
Serial.begin(9600);
pinMode(trig, OUTPUT);
pinMode(echo, INPUT);
Serial.println("test");
pinMode(buzzerPin, OUTPUT);
  lcd.init(); // initialize the lcd
  lcd.backlight();
}

unsigned long time, distance;
void loop() 
{
  digitalWrite(trig,HIGH);
 delayMicroseconds(10);
 digitalWrite(trig, LOW);
 time = pulseIn(echo, HIGH);
 distance=time/58;
 Serial.print("distance= ");
 Serial.println(distance);
 delay(100);
 if(distance<100){
   noTone(buzzerPin);
     lcd.clear();                 // clear display
  //lcd.setCursor(0, 0);         // move cursor to   (0, 0)
 // lcd.print("");        // print message at (0, 0)
  lcd.setCursor(0, 1);         // move cursor to   (2, 1)
  lcd.print("battery is full "); // print message at (2, 1)
  delay(1000);                 // display the above for two seconds

 }
 else if (distance>=100){
   lcd.print("battery is empty"); // print message at (0, 1)
  delay(1000);
  tone(1,distance );
  delay(5000);
  noTone(1);
    lcd.clear();                  // clear display
 // lcd.setCursor(3, 0);          // move cursor to   (3, 0)
  //lcd.print("");        // print message at (3, 0)
  lcd.setCursor(0, 1);          // move cursor to   (0, 1)
 
 }

}