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

LiquidCrystal_I2C lcd(0x27, 20, 4); // I2C address 0x27, 20 columns, 4 rows

const int trigPin = 9;    // Connect the trigger pin of the ultrasonic sensor to digital pin 9
const int echoPin = 10;   // Connect the echo pin of the ultrasonic sensor to digital pin 10
const int buzzerPin = 11; // Connect the positive (longer leg) of the buzzer to digital pin 11

int set_val = 20; // Set your desired water level threshold in centimeters

void setup() {
  Serial.begin(9600);
  lcd.begin(20, 4); // Initialize the LCD with 20 columns and 4 rows
  lcd.print("WATER LEVEL:");

  pinMode(trigPin, OUTPUT);
  pinMode(echoPin, INPUT);
  pinMode(buzzerPin, OUTPUT);
}

void loop() {
  long duration, inches;

  // Send a pulse to the trigger pin to start the measurement
  digitalWrite(trigPin, LOW);
  delayMicroseconds(2);
  digitalWrite(trigPin, HIGH);
  delayMicroseconds(10);
  digitalWrite(trigPin, LOW);

  // Measure the duration of the echo pulse
  duration = pulseIn(echoPin, HIGH);

  // Calculate the distance in centimeters (divide by 58 because the speed of sound is approximately 343 meters per second)
  inches = duration / 58.0;

  // Print the distance to the serial monitor
  Serial.print("Distance: ");
  Serial.print(inches);
  Serial.println(" cm");

  // Map the distance to a percentage range
  int percentage = map(inches, 0, set_val, 100, 0);
  percentage = constrain(percentage, 0, 100); // Ensure the percentage is within 0-100 range

  // Display the percentage on the LCD
  lcd.clear();
  lcd.setCursor(0, 0);
  lcd.print("Percentage: ");
  lcd.print(percentage);
  lcd.print("%");

  // Check if the distance is below a certain threshold (adjust as needed)
  if (inches < set_val) {
    // If the distance is below the threshold, make a sound with the buzzer
    tone(buzzerPin, 1000); // Change the frequency as needed
    delay(500);           // Sound duration (adjust as needed)
    noTone(buzzerPin);
  }

  delay(500); // Wait for a short duration before the next measurement
}