ultrasonic_sensor.ino

// C++ code
// https://learn.adafruit.com/i2c-spi-lcd-backpack/arduino-i2c-use
#include <Adafruit_LiquidCrystal.h>

int seconds = 0;
int trigger = 6;
int echo = 2;
Adafruit_LiquidCrystal lcd_1(0);

void setup()
{
  lcd_1.begin(16, 2);
  lcd_1.print("hello world");
  pinMode(trigger,OUTPUT);
  pinMode(echo,INPUT);
}

void loop()
{

  float distance    = 0.0;
  float finalvalue  = 0.0;
  digitalWrite(trigger,LOW);
  delayMicroseconds(4);
  digitalWrite(trigger,HIGH);
  delayMicroseconds(10);
  digitalWrite(trigger,LOW);

  distance = pulseIn(echo,HIGH);
  finalvalue = (distance/28.57)/2;
  lcd_1.setCursor(0, 1);
  lcd_1.print(finalvalue);


  seconds += 1;
}