Wokwi - Online ESP32, STM32, Arduino Simulator

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

// Ultrasonic sensor pins
#define TRIG_PIN 5
#define ECHO_PIN 18

// LED pins
#define RED_LED 23
#define YELLOW_LED 22
#define GREEN_LED 21

// Tank dimensions (adjust)
const int TANK_HEIGHT = 30; // cm

// Wi-Fi credentials
const char* ssid = "Wokwi-GUEST";       // Wokwi simulation WiFi
const char* password = "";

// Web server on port 80
WebServer server(80);

// LCD setup (I2C address 0x27 is most common, change to 0x3F if needed)
LiquidCrystal_I2C lcd(0x27, 16, 2);

long readUltrasonicDistance() {
  digitalWrite(TRIG_PIN, LOW);
  delayMicroseconds(2);
  digitalWrite(TRIG_PIN, HIGH);
  delayMicroseconds(10);
  digitalWrite(TRIG_PIN, LOW);

  long duration = pulseIn(ECHO_PIN, HIGH);
  long distance = duration * 0.034 / 2; // cm
  return distance;
}

void handleRoot() {
  long distance = readUltrasonicDistance();
  int waterLevel = TANK_HEIGHT - distance;
  if (waterLevel < 0) waterLevel = 0;

  int percent = (waterLevel * 100) / TANK_HEIGHT;

  String html = "<!DOCTYPE html><html><head><meta name='viewport' content='width=device-width, initial-scale=1'>";
  html += "<style>body{font-family:Arial;text-align:center;} .level{font-size:24px;}</style></head><body>";
  html += "<h1>ESP32 Water Level Indicator</h1>";
  html += "<p class='level'>Water Level: " + String(waterLevel) + " cm</p>";
  html += "<p>Tank Capacity: " + String(percent) + "%</p>";
  html += "</body></html>";

  server.send(200, "text/html", html);
}

void updateLEDs(int percent) {
  if (percent <= 20) {          // Low level
    digitalWrite(RED_LED, HIGH);
    digitalWrite(YELLOW_LED, LOW);
    digitalWrite(GREEN_LED, LOW);
  } else if (percent > 20 && percent < 80) {  // Medium level
    digitalWrite(RED_LED, LOW);
    digitalWrite(YELLOW_LED, HIGH);
    digitalWrite(GREEN_LED, LOW);
  } else {                      // Full level
    digitalWrite(RED_LED, LOW);
    digitalWrite(YELLOW_LED, LOW);
    digitalWrite(GREEN_LED, HIGH);
  }
}

void setup() {
  Serial.begin(115200);
  pinMode(TRIG_PIN, OUTPUT);
  pinMode(ECHO_PIN, INPUT);

  pinMode(RED_LED, OUTPUT);
  pinMode(YELLOW_LED, OUTPUT);
  pinMode(GREEN_LED, OUTPUT);

  // LCD setup
  lcd.init();
  lcd.backlight();
  lcd.setCursor(0, 0);
  lcd.print("Connecting WiFi");

  // Wi-Fi setup
  WiFi.begin(ssid, password);
  Serial.print("Connecting to WiFi");
  while (WiFi.status() != WL_CONNECTED) {
    delay(500);
    Serial.print(".");
  }
  Serial.println("\nConnected to WiFi");
  Serial.println(WiFi.localIP());

  lcd.clear();
  lcd.setCursor(0, 0);
  lcd.print("WiFi Connected");
  lcd.setCursor(0, 1);
  lcd.print(WiFi.localIP());

  // Start server
  server.on("/", handleRoot);
  server.begin();
}

void loop() {
  server.handleClient();

  // Measure water level
  long distance = readUltrasonicDistance();
  int waterLevel = TANK_HEIGHT - distance;
  if (waterLevel < 0) waterLevel = 0;
  int percent = (waterLevel * 100) / TANK_HEIGHT;

  // Update LEDs
  updateLEDs(percent);

  // Update LCD
  lcd.clear();
  lcd.setCursor(0, 0);
  lcd.print("Level:");
  lcd.print(waterLevel);
  lcd.print("cm");
  lcd.setCursor(0, 1);
  lcd.print("Tank:");
  lcd.print(percent);
  lcd.print("%");

  // Debug output
  Serial.print("Water Level: ");
  Serial.print(waterLevel);
  Serial.print(" cm (");
  Serial.print(percent);
  Serial.println("%)");
  
  delay(2000);
}