Arduino ultrasonic sensor (HC-SR04) to a 16x2 LCD display a

 To connect an Arduino ultrasonic sensor (HC-SR04) to a 16x2 LCD display and show the measured distance, you'll need to use the LiquidCrystal library for the LCD and follow these steps:

Hardware Required:

1. Arduino board (e.g., Uno, Nano)
2. HC-SR04 ultrasonic sensor
3. 16x2 LCD display (with I2C adapter or without I2C)
4. Breadboard and jumper wires

Connections:

For LCD with I2C Adapter:

1. HC-SR04 to Arduino:

   • VCC to Arduino 5V
   • GND to Arduino GND
   • TRIG to Arduino Digital Pin 9
   • ECHO to Arduino Digital Pin 10

2. LCD (with I2C adapter) to Arduino:

   • VCC to Arduino 5V
   • GND to Arduino GND
   • SDA to Arduino A4 (on an Uno) or SDA pin (on other boards)
   • SCL to Arduino A5 (on an Uno) or SCL pin (on other boards)

For LCD without I2C Adapter:

1. LCD to Arduino:
   • VSS to Arduino GND
   • VDD to Arduino 5V
   • V0 to the middle pin of a potentiometer (for contrast adjustment)
   • RS to Arduino Digital Pin 12
   • RW to Arduino GND
   • E to Arduino Digital Pin 11
   • D0 to Arduino GND (usually not used)
   • D1 to Arduino GND (usually not used)
   • D2 to Arduino Digital Pin 7
   • D3 to Arduino Digital Pin 6
   • D4 to Arduino Digital Pin 5
   • D5 to Arduino Digital Pin 4
   • D6 to Arduino Digital Pin 3
   • D7 to Arduino Digital Pin 2
   • A to Arduino 5V (Backlight Anode)
   • K to Arduino GND (Backlight Cathode)

Code:

Here is the code to interface the HC-SR04 with the 16x2 LCD:

For LCD with I2C Adapter:

cpp
#include <Wire.h>
#include <LiquidCrystal_I2C.h>

LiquidCrystal_I2C lcd(0x27, 16, 2); // Change address if needed, 0x27 is common for I2C LCDs

const int trigPin = 9;
const int echoPin = 10;

void setup() {
  lcd.begin();
  lcd.backlight(); // Turn on the backlight if available
  lcd.setCursor(0, 0);
  lcd.print("Distance: ");
  
  pinMode(trigPin, OUTPUT);
  pinMode(echoPin, INPUT);
}

void loop() {
  long duration;
  int distance;

  digitalWrite(trigPin, LOW);
  delayMicroseconds(2);

  digitalWrite(trigPin, HIGH);
  delayMicroseconds(10);
  digitalWrite(trigPin, LOW);

  duration = pulseIn(echoPin, HIGH);
  distance = (duration / 2) / 29.1;

  lcd.setCursor(0, 1);
  lcd.print("                "); // Clear previous data
  lcd.setCursor(0, 1);
  lcd.print(distance);
  lcd.print(" cm");
  
  delay(500);
}

For LCD without I2C Adapter:

cpp
#include <LiquidCrystal.h>

LiquidCrystal lcd(12, 11, 10, 9, 8, 7); // Pin numbers for LCD without I2C

const int trigPin = 6;
const int echoPin = 5;

void setup() {
  lcd.begin(16, 2);
  lcd.print("Distance: ");
  
  pinMode(trigPin, OUTPUT);
  pinMode(echoPin, INPUT);
}

void loop() {
  long duration;
  int distance;

  digitalWrite(trigPin, LOW);
  delayMicroseconds(2);

  digitalWrite(trigPin, HIGH);
  delayMicroseconds(10);
  digitalWrite(trigPin, LOW);

  duration = pulseIn(echoPin, HIGH);
  distance = (duration / 2) / 29.1;

  lcd.setCursor(0, 1);
  lcd.print("                "); // Clear previous data
  lcd.setCursor(0, 1);
  lcd.print(distance);
  lcd.print(" cm");
  
  delay(500);
}

Explanation:

1. Libraries and Initialization:

   • Wire.h and LiquidCrystal_I2C.h are used for I2C communication and controlling the LCD.
   • For a standard LCD, LiquidCrystal.h is used.
   • lcd.begin() initializes the LCD. For I2C, specify the address (e.g., 0x27) and dimensions (16x2).

2. Setup Function:

   • lcd.print("Distance: "); displays a static label on the LCD.
   • pinMode(trigPin, OUTPUT); and pinMode(echoPin, INPUT); set up the pins.

3. Loop Function:

   • Send a pulse via the TRIG pin and measure the echo duration using pulseIn().
   • Calculate distance in centimeters.
   • Update the LCD display with the new distance. The previous data is cleared by printing spaces before the new distance value.