Smart water level measurement with Arduino UNO and HC-SR04

Arduino 10-05-26

3880 1

Tutorial plan

1- Objective of the project

2- Required Components

3- Circuit Connections of system

4- Arduino program

Objective of the project

The objective of this project is to create a smart water level measurement system using an Arduino Uno, an HC-SR04 Ultrasonic Sensor, and an LCD display.

The system is designed to measure the water level in real time without direct contact with the liquid.

The measured level is then displayed on the LCD screen using graphical bars, allowing users to easily monitor the amount of water inside a tank, container, or reservoir.

Functionment

The HC-SR04 Ultrasonic Sensor is placed above the water tank to continuously send ultrasonic waves toward the water surface.

When these waves hit the water, they are reflected back to the sensor. The sensor calculates the distance between itself and the water surface based on the travel time of the ultrasonic waves.

Next, the Arduino Uno processes the received distance data and converts it into a water level value. According to the measured level, the Arduino generates graphical bars on the LCD display.

As the water level increases, more bars appear on the screen, and as the level decreases, fewer bars are displayed.

This graphical representation makes the monitoring system simple, clear, and user-friendly.

Required Components

1. Arduino UNO

Arduino Uno

The Arduino UNO is the main controller of the system. It receives the distance measurements from the ultrasonic sensor, processes the data, calculates the water level, and sends the results to the LCD display. It also controls the graphical bar display according to the measured water level.

2. HC-SR04 sensor

HC-SR04

The HC-SR04 sensor is used to measure the distance between the sensor and the water surface. It sends ultrasonic waves toward the water and receives the reflected waves to calculate the water level.

3. LCD Display with I2C Module

The LCD display is used to show the measured water level in real time. It can display text information as well as graphical bars that represent the amount of water in the tank. This makes the monitoring system easy to understand and visually interactive.

4. Jumper Wires

Jumper wires

Jumper wires are used to connect the Arduino UNO, FC-51 sensor, and LCD display together. They ensure proper electrical connections between all components.

Circuit Connections of system

1- Connection of HC-SR04 sensor to Arduino UNO

HC-SR04 sensor	Arduino UNO
VCC	5V
GND	GND
Trig	D2
Echo	D3

2- Connection of LCD I2C display to Arduino UNO

LCD I2C display	Arduino UNO
VCC	5V
GND	GND
SDA	A4
SCL	A5

Arduino program of system

This Arduino program is designed to measure the water level in real time using an HC-SR04 Ultrasonic Sensor, an Arduino Uno, and an I2C LCD display. The system continuously calculates the amount of water inside a tank or container and displays the result as a percentage and as graphical bars on the LCD screen.

You need to install this library : LiquidCrystal_I2C for I2C LCD screen.

#include <Wire.h>                 // Library for I2C communication
#include <LiquidCrystal_I2C.h>   // Library for I2C LCD display

// Initialize the I2C LCD display
// I2C address = 0x27, LCD with 16 columns and 2 rows
LiquidCrystal_I2C lcd(0x27, 16, 2);

// ==============================
// HC-SR04 Sensor Configuration
// ==============================
#define TRIG_PIN 2   // TRIG pin connected to digital pin 2
#define ECHO_PIN 3   // ECHO pin connected to digital pin 3

// Maximum height of the tank or glass (in cm)
#define MAX_HEIGHT 8.5

// ==============================
// Custom characters creation
// for the progress bar display
// ==============================

// Empty bar
byte bar0[8] = {0,0,0,0,0,0,0,0};

// 20% filled bar
byte bar1[8] = {16,16,16,16,16,16,16,16};

// 40% filled bar
byte bar2[8] = {24,24,24,24,24,24,24,24};

// 60% filled bar
byte bar3[8] = {28,28,28,28,28,28,28,28};

// 80% filled bar
byte bar4[8] = {30,30,30,30,30,30,30,30};

// 100% filled bar
byte bar5[8] = {31,31,31,31,31,31,31,31};

// Variables for measurements
long duration;     // Echo return time
float distance;    // Measured distance

void setup() {

  // Configure sensor pins
  pinMode(TRIG_PIN, OUTPUT);
  pinMode(ECHO_PIN, INPUT);

  // Initialize the LCD display
  lcd.init();

  // Turn on the LCD backlight
  lcd.backlight();

  // ==============================
  // Create custom LCD characters
  // ==============================
  lcd.createChar(0, bar0);
  lcd.createChar(1, bar1);
  lcd.createChar(2, bar2);
  lcd.createChar(3, bar3);
  lcd.createChar(4, bar4);
  lcd.createChar(5, bar5);

  // Display project title
  lcd.setCursor(0,0);
  lcd.print("Water Level");
}

void loop() {

  // ==============================
  // Measure distance using HC-SR04
  // ==============================

  // Send ultrasonic pulse
  digitalWrite(TRIG_PIN, LOW);
  delayMicroseconds(2);

  digitalWrite(TRIG_PIN, HIGH);
  delayMicroseconds(10);

  digitalWrite(TRIG_PIN, LOW);

  // Read echo return time
  duration = pulseIn(ECHO_PIN, HIGH);

  // Calculate distance in centimeters
  distance = duration * 0.034 / 2;

  // Calculate water level
  // 2.3 is used for sensor calibration adjustment
  float waterLevel = MAX_HEIGHT - (distance - 2.3);

  // Prevent negative values
  if (waterLevel < 0)
    waterLevel = 0;

  // Prevent values higher than maximum height
  if (waterLevel > MAX_HEIGHT)
    waterLevel = MAX_HEIGHT;

  // ==============================
  // Convert water level to percentage
  // ==============================
  int percent = (waterLevel / MAX_HEIGHT) * 100;

  // ==============================
  // Display percentage on LCD
  // ==============================
  lcd.setCursor(0,1);

  // Create display string
  String value_display = String(percent) + "%  ";

  // Print percentage
  lcd.print(value_display);

  // ==============================
  // Display graphical progress bar
  // ==============================

  // Total number of bar segments
  int totalBars = 10;

  // Convert percentage into bar blocks
  int filled = map(percent, 0, 100, 0, totalBars * 5);

  // Set cursor position after percentage
  lcd.setCursor(5,1);

  // Loop to draw the 10 bar segments
  for (int i = 0; i < totalBars; i++) {

    // Calculate fill level of each segment
    int barLevel = filled - (i * 5);

    // Display corresponding custom character
    if (barLevel >= 5)
      lcd.write(5);   // Fully filled bar

    else if (barLevel > 0)
      lcd.write(barLevel); // Partially filled bar

    else
      lcd.write(0);   // Empty bar
  }

  // Wait before next measurement
  delay(500);
}

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#include <Wire.h> // Library for I2C communication

#include <LiquidCrystal_I2C.h> // Library for I2C LCD display

// Initialize the I2C LCD display

// I2C address = 0x27, LCD with 16 columns and 2 rows

LiquidCrystal_I2C lcd(0x27, 16, 2);

// ==============================

// HC-SR04 Sensor Configuration

// ==============================

#define TRIG_PIN 2 // TRIG pin connected to digital pin 2

#define ECHO_PIN 3 // ECHO pin connected to digital pin 3

// Maximum height of the tank or glass (in cm)

#define MAX_HEIGHT 8.5

// ==============================

// Custom characters creation

// for the progress bar display

// ==============================

// Empty bar

byte bar0[8] = {0,0,0,0,0,0,0,0};

// 20% filled bar

byte bar1[8] = {16,16,16,16,16,16,16,16};

// 40% filled bar

byte bar2[8] = {24,24,24,24,24,24,24,24};

// 60% filled bar

byte bar3[8] = {28,28,28,28,28,28,28,28};

// 80% filled bar

byte bar4[8] = {30,30,30,30,30,30,30,30};

// 100% filled bar

byte bar5[8] = {31,31,31,31,31,31,31,31};

// Variables for measurements

long duration; // Echo return time

float distance; // Measured distance

void setup() {

// Configure sensor pins

pinMode(TRIG_PIN, OUTPUT);

pinMode(ECHO_PIN, INPUT);

// Initialize the LCD display

lcd.init();

// Turn on the LCD backlight

lcd.backlight();

// ==============================

// Create custom LCD characters

// ==============================

lcd.createChar(0, bar0);

lcd.createChar(1, bar1);

lcd.createChar(2, bar2);

lcd.createChar(3, bar3);

lcd.createChar(4, bar4);

lcd.createChar(5, bar5);

// Display project title

lcd.setCursor(0,0);

lcd.print("Water Level");

}

void loop() {

// ==============================

// Measure distance using HC-SR04

// ==============================

// Send ultrasonic pulse

digitalWrite(TRIG_PIN, LOW);

delayMicroseconds(2);

digitalWrite(TRIG_PIN, HIGH);

delayMicroseconds(10);

digitalWrite(TRIG_PIN, LOW);

// Read echo return time

duration = pulseIn(ECHO_PIN, HIGH);

// Calculate distance in centimeters

distance = duration * 0.034 / 2;

// Calculate water level

// 2.3 is used for sensor calibration adjustment

float waterLevel = MAX_HEIGHT - (distance - 2.3);

// Prevent negative values

if (waterLevel < 0)

waterLevel = 0;

// Prevent values higher than maximum height

if (waterLevel > MAX_HEIGHT)

waterLevel = MAX_HEIGHT;

// ==============================

// Convert water level to percentage

// ==============================

int percent = (waterLevel / MAX_HEIGHT) * 100;

// ==============================

// Display percentage on LCD

// ==============================

lcd.setCursor(0,1);

// Create display string

String value_display = String(percent) + "% ";

// Print percentage

lcd.print(value_display);

// ==============================

// Display graphical progress bar

// ==============================

// Total number of bar segments

int totalBars = 10;

// Convert percentage into bar blocks

int filled = map(percent, 0, 100, 0, totalBars * 5);

// Set cursor position after percentage

lcd.setCursor(5,1);

// Loop to draw the 10 bar segments

for (int i = 0; i < totalBars; i++) {

// Calculate fill level of each segment

int barLevel = filled - (i * 5);

// Display corresponding custom character

if (barLevel >= 5)

lcd.write(5); // Fully filled bar

else if (barLevel > 0)

lcd.write(barLevel); // Partially filled bar

else

lcd.write(0); // Empty bar

}

// Wait before next measurement

delay(500);

}

At the beginning of the program, the necessary libraries for I2C communication and LCD control are included. The LCD display is then initialized with its I2C address and screen dimensions. The TRIG and ECHO pins of the ultrasonic sensor are configured to allow the Arduino UNO to communicate with the sensor and measure distances.

The program also creates several custom LCD characters that represent different bar fill levels. These custom characters are used to build a graphical progress bar on the LCD display, making the water level visualization more interactive and easier to understand.

Inside the loop() function, the Arduino sends an ultrasonic pulse through the HC-SR04 sensor. The sensor measures the time taken for the ultrasonic waves to travel to the water surface and return back. Using this time, the Arduino calculates the distance between the sensor and the water surface.

Next, the program converts the measured distance into a water level value based on the maximum tank height. The water level is then transformed into a percentage value. This percentage is displayed on the LCD screen together with a graphical bar indicator that increases or decreases according to the amount of water detected in the container.

Finally, the system repeats the measurement every 500 milliseconds, allowing continuous real-time monitoring of the water level.