Water Level Indicator With LCD Display

Last revision • 25/06/2025

HARDWARE REQUIRED:

PICUNO Microcontroller board
1 × 16x2 I2C LCD Display
1 × HW-038 Water Level Sensor
Jumper wires
USB cable
1 × 4xAA Battery pack (for external power supply)

DESCRIPTION:

This project creates a smart water level indicator for a container. It uses a water level sensor to measure how submerged it is and reports the status on an I2C LCD screen. When the tank is at a low level, the display reads "Status: EMPTY". When the water reaches a medium level, it changes to "Status: MEDIUM". When the tank is full and at risk of overflowing, the display reads "Status: FULL!" and a buzzer sounds a continuous alarm.

LIBRARIES REQUIRED:
For C / Arduino IDE:
Wire.h: Manages I2C communication (usually included by default).
LiquidCrystal_I2C.h: The driver library for the I2C LCD module.

For Micropython / Thonny IDE:
i2c_lcd.py: The custom library file saved to the PICUNO board.
The code also uses the built-in machine and time modules.

CIRCUIT DIAGRAM:

16x2 I2C LCD display:

Connect the LCD Module's GND pin to GND.
Connect the LCD Module's VCC pin to the Positive (+) terminal of the 4xAA Battery Pack.
Connect the LCD Module's SDA pin GPIO 4 (SDA Pin on PICUNO).
Connect the LCD Module's SCL pin GPIO 5 (SCL Pin on PICUNO).
Connect the negative terminal (-) of the 4xAA Battery Pack to Common GND on breadboard.

Water Level Sensor:

Connect the VCC (+) pin to 5V pin on the board.
Connect the GND (-) pin to GND pin on board.
Connect the Signal (S) pin to Analog Pin A0 (GPIO 26).

Buzzer Module:

Connect the GND (-) pin to GND pin.
Connect the VCC (+) pin to 5V.
Connect the Signal (S) pin to GPIO 8.

SCHEMATIC:

16x2 I2C LCD Display:

LCD VCC → 4xAA Battery Pack (+)

LCD GND → GND

LCD SDA → GPIO 4 (Board SDA Pin)

LCD SCL → GPIO 5 (Board SCL Pin)

Water Level Sensor:

GND / (-) → GND

VCC / (+) → 5V

SIGNAL / (S) → A0 (GPIO 26)

Buzzer Module:

VCC / (+) → 5V

GND / (-) → GND

Signal (S) → GPIO 8

Common Ground Connection:

4xAA Battery Pack (-) → PICUNO Board GND

CODE -- C:

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

const int SENSOR_PIN = A0;
const int BUZZER_PIN = 8;

// --- LCD Setup ---
LiquidCrystal_I2C lcd(0x27, 16, 2);

// --- Calibration Thresholds ---
const int MEDIUM_LEVEL = 200;
const int FULL_LEVEL = 400;

void setup() {
  Serial.begin(9600);
  pinMode(BUZZER_PIN, OUTPUT);
  lcd.init();
  lcd.backlight();
}

void loop() {
  int waterLevel = analogRead(SENSOR_PIN);

  Serial.print("Water Level Reading: ");
  Serial.println(waterLevel);

  lcd.clear();
  lcd.setCursor(0, 0);
  lcd.print("Water Level");
  lcd.setCursor(0, 1);

  if (waterLevel < MEDIUM_LEVEL) {
    lcd.print("Status: EMPTY ");
    noTone(BUZZER_PIN);
  }
  else if (waterLevel >= MEDIUM_LEVEL && waterLevel < FULL_LEVEL) {
    lcd.print("Status: MEDIUM");
    noTone(BUZZER_PIN);
  }
  else {
    lcd.print("Status: FULL! ");
    tone(BUZZER_PIN, 1500);
  }

  delay(200);
}

Thresholds - The MEDIUM_LEVEL and FULL_LEVEL variables define the trigger points for the different statuses.

lcd.print() - This command is used to display the current status text on the LCD screen.

if / else if / else Logic - This structure checks the waterLevel reading and selects the correct message to display.

CODE -- PYTHON:

from machine import Pin, ADC, PWM, I2C
from time import sleep
from i2c_lcd import I2cLcd

sensor = ADC(Pin(26))
buzzer = PWM(Pin(8))
i2c = I2C(0, scl=Pin(5), sda=Pin(4))
lcd = I2cLcd(i2c, 0x27, 2, 16)

# --- Calibration Thresholds ---
MEDIUM_LEVEL = 15000
FULL_LEVEL = 30000

# --- Main Loop ---
while True:
    water_level = sensor.read_u16()

    print(f"Water Level Reading: {water_level}")

    lcd.clear()
    lcd.putstr("Water Level")
    lcd.move_to(0, 1)

    if water_level < MEDIUM_LEVEL:
        # EMPTY or LOW
        lcd.putstr("Status: EMPTY ")
        buzzer.duty_u16(0)
    elif water_level >= MEDIUM_LEVEL and water_level < FULL_LEVEL:
        # MEDIUM
        lcd.putstr("Status: MEDIUM")
        buzzer.duty_u16(0)
    else:
        # FULL / OVERFLOW
        lcd.putstr("Status: FULL! ")
        buzzer.freq(2500)
        buzzer.duty_u16(32768)

    sleep(0.2)

Thresholds - These variables define the trigger points for the medium and full levels, using the 16-bit ADC range.

lcd.putstr() - This library command prints a string of text to the LCD at the current cursor position.

if / elif / else Logic - This structure is used to check the water_level reading and display the correct status message on the LCD.