Ultrasonic Distance Meter

Steps

1. Wire the sensor

   HC-SR04: VCC to 5V, GND to GND, Trig to D9, Echo to D10.

2. Wire the LCD

   I2C LCD: VCC to 5V, GND to GND, SDA to A4, SCL to A5 (Nano / UNO).

3. Install the library

   In the Arduino IDE install the LiquidCrystal_I2C library.

4. Upload

   Upload the sketch. If the screen is blank, adjust the contrast screw on the backpack or change the address to 0x3F.

Code

#include <Wire.h>
#include <LiquidCrystal_I2C.h>
LiquidCrystal_I2C lcd(0x27, 16, 2);
const int TRIG = 9, ECHO = 10;

void setup() {
  pinMode(TRIG, OUTPUT); pinMode(ECHO, INPUT);
  lcd.init(); lcd.backlight();
}

void loop() {
  digitalWrite(TRIG, LOW);  delayMicroseconds(2);
  digitalWrite(TRIG, HIGH); delayMicroseconds(10);
  digitalWrite(TRIG, LOW);
  long us = pulseIn(ECHO, HIGH, 30000);
  lcd.clear();
  lcd.setCursor(0, 0); lcd.print("Distance:");
  lcd.setCursor(0, 1);
  if (us == 0) lcd.print("Out of range");
  else { lcd.print(us * 0.0343 / 2, 1); lcd.print(" cm"); }
  delay(300);
}