IoT Fire Detection & Alert System – ESP32 + MQ-2 + DHT22 | MakeMindz Skip to main content 🚨 Simulate

ESP32 · IoT · Intermediate–Advanced

IoT Fire Detection
& Alert System

Multi-sensor fire monitoring with MQ-2 smoke, DHT22 temperature, and IR flame sensors. 4-level automated response — auto-sprinkler, buzzer patterns, and a live web dashboard.

🔌 ESP32 DevKit 💨 MQ-2 Smoke 🌡️ DHT22 Temp 🔥 Flame Sensor 📺 OLED Display 🌐 Web Dashboard 🆓 Free on Wokwi

🚨 Open Free Simulation 📋 Step-by-Step Guide

🖥️ Platform: Wokwi — Free, Online, No Installation Required

Run the complete IoT fire detection circuit in your browser. Simulate fire scenarios in seconds.

🔗 Open Simulation →

00 · Overview

What You'll Build

This advanced IoT project uses an ESP32 to monitor for fire conditions using three independent sensors. When a hazard is detected, the system escalates through 4 alert levels with visual LEDs, buzzer patterns, automatic safety systems, and a live web dashboard accessible from any device on the same network.

📡

Triple Sensor

MQ-2 smoke, DHT22 temperature, and IR flame detection simultaneously

🚨

4-Level Alerts

SAFE → WARNING → DANGER → CRITICAL with different responses

🚿

Auto-Sprinkler

Automatically activates when CRITICAL level is reached

💨

Exhaust Fan

Turns on automatically when smoke exceeds 30%

🌐

Web Dashboard

Live sensor data with progress bars, auto-refresh every 2 seconds

📱

Alert Simulation

Simulated SMS, email, and push notification alerts on DANGER+

📺

OLED Display

128×64 SSD1306 shows live sensor readings and system status

📊

Data Logging

Alert history stored in a rolling 10-entry log with timestamps

01 · Components

Components Required

All components are available as virtual parts in Wokwi — potentiometers simulate the MQ-2 and flame sensors.

Bill of materials for the IoT Fire Detection System
#	Component	Qty	Role
1	ESP32 DevKit V1	×1	Main controller with built-in WiFi for web dashboard
2	MQ-2 Gas/Smoke Sensor	×1	Detects smoke and gas levels 0–100% (simulated by potentiometer in Wokwi)
3	DHT22 Temperature & Humidity	×1	Monitors temperature (°C) and humidity (%RH)
4	Flame Sensor (IR)	×1	Infrared flame detection 0–100% (simulated by potentiometer)
5	Buzzer (Active)	×1	Audible alarm with different patterns per alert level
6	Red LED + 220Ω	×1	DANGER indicator
7	Green LED + 220Ω	×1	SAFE indicator
8	Blue LED + 220Ω	×1	WARNING indicator
9	Cyan LED + 220Ω	×1	Sprinkler active indicator
10	White LED + 220Ω	×1	Exhaust fan active indicator
11	SSD1306 OLED 128×64 (I2C)	×1	Shows live sensor values and system status
12	Jumper Wires	×~20	All component connections

ℹ️ In Wokwi, the MQ-2 and flame sensors are represented by potentiometers. Rotating the dial simulates increasing smoke or flame detection levels — this is the standard Wokwi approach for analog sensors.

02 · Alert System

4-Level Alert System

The system continuously evaluates all three sensors and escalates or de-escalates the alert level automatically.

Level 0

🟢

SAFE

Green LED on. No alarm. All systems on standby.

Level 1

🔵

WARNING

Blue LED on. No alarm. Monitor closely. Exhaust fan may activate.

Level 2

🔴

DANGER

Red LED on. Medium beeping. Alarm activated. Alerts sent. Fan ON.

Level 3

🚨

CRITICAL

Red LED flashing fast. Rapid beeping. Sprinkler activated. Emergency alerts.

Sensor Thresholds

Sensor	WARNING	DANGER	CRITICAL
🌡️ Temperature	≥ 35°C	≥ 45°C	≥ 55°C
💨 Smoke Level	≥ 30%	≥ 50%	≥ 70%
🔥 Flame Detection	Not triggered	Not triggered	≥ 40%

🚨 Alert levels use the worst-case sensor reading. If any single sensor reaches CRITICAL threshold, the entire system goes to CRITICAL — even if other sensors are normal.

03 · Circuit Wiring

Pin Connections

Paste the diagram.json (next section) to auto-wire everything. This table is for reference.

All ESP32 pin connections
Component	Component Pin	ESP32 Pin	Wire
DHT22	VCC	3.3V	Red
DHT22	GND	GND	Black
DHT22	DATA	D15	Green
MQ-2 Smoke	VCC	3.3V	Red
MQ-2 Smoke	GND	GND	Black
MQ-2 Smoke	Signal (AOUT)	D34 (analog input)	Orange
Flame Sensor	VCC	3.3V	Red
Flame Sensor	GND	GND	Black
Flame Sensor	Signal (AOUT)	D35 (analog input)	Yellow
Red LED (via 220Ω)	Anode	D26	Red
Green LED (via 220Ω)	Anode	D27	Green
Blue LED (via 220Ω)	Anode	D14	Blue
Cyan LED (Sprinkler, 220Ω)	Anode	D12	Cyan
White LED (Fan, 220Ω)	Anode	D13	White
All LED Cathodes	Cathode	GND	Black
Buzzer	Pin 1 (+)	D25	Purple
Buzzer	Pin 2 (–)	GND	Black
OLED SSD1306	VCC	3.3V	Red
OLED SSD1306	GND	GND	Black
OLED SSD1306	SDA	D21 (I2C)	Blue
OLED SSD1306	SCL	D22 (I2C)	Yellow

04 · Step-by-Step Setup

Complete Setup Guide

Follow these steps in order to get the simulation running in under 5 minutes.

🌐 Open Wokwi & Start a New ESP32 Project

Go to wokwi.com in any modern browser (Chrome, Firefox, or Edge).

Click "New Project" on the homepage
Select "ESP32" from the board list
A blank canvas appears with the ESP32 DevKit already placed

💡 Create a free Wokwi account to save your project and share it with a link. Teachers can view the full simulation without any software.

📋 Paste the diagram.json — Auto-Wire in One Click

The fastest way to set up the circuit is to use the diagram.json file.

Click the "diagram.json" tab next to sketch.ino
Select all text (Ctrl+A) and delete it
Paste the complete JSON from the diagram.json section below
Press Ctrl+S — all components appear and wire themselves ✅

⚠️ Copy the complete JSON — it starts with { and ends with }. Don't miss any brackets or the circuit will not load correctly.

📚 Install Required Libraries

Create a libraries.txt file in Wokwi and paste these three lines:

libraries.txt

DHT sensor library
Adafruit GFX Library
Adafruit SSD1306

💡 Click the "+" icon next to the file tabs to create libraries.txt. Wokwi auto-downloads all three libraries when you start the simulation.

💻 Paste the Arduino Code

Click the sketch.ino tab, delete any existing code, and paste the complete code from the Code section below.

The WiFi credentials are pre-set to "Wokwi-GUEST" — no changes needed
Press ▶ Play to start the simulation
Watch the OLED display show "FIRE DETECTION SYSTEM" then "Initializing..."
The buzzer plays a startup tone and the green LED lights up (SAFE)

🔗 Use the Pre-Built Simulation

Skip all setup — the complete circuit and code is already built for you:

Open Complete Fire Detection Simulation

ESP32 + all sensors + OLED + buzzer + LEDs. Click ▶ Play, then rotate the sensor dials to trigger alerts!

🚨 Launch Simulation →

05 · Arduino Code

The Complete Sketch

Paste this into sketch.ino in Wokwi. The code is organised into clean sections for each system feature.

sketch.ino — IoT Fire Detection System (Part 1: Setup & Config)

/*
 * IoT-Based Fire Detection & Alert System
 * ESP32 + MQ-2 + DHT22 + Flame Sensor + OLED + Web Dashboard
 * MakeMindz Summer Course
 */

#include <WiFi.h>
#include <WebServer.h>
#include <DHT.h>
#include <Wire.h>
#include <Adafruit_GFX.h>
#include <Adafruit_SSD1306.h>

// ── WiFi (Wokwi Guest Network) ────────────────
const char* ssid     = "Wokwi-GUEST";
const char* password = "";
WebServer server(80);

// ── Pin Definitions ───────────────────────────
#define DHT_PIN        15
#define MQ2_PIN        34  // Analog input
#define FLAME_PIN      35  // Analog input
#define BUZZER_PIN     25
#define RED_LED_PIN    26  // DANGER
#define GREEN_LED_PIN  27  // SAFE
#define BLUE_LED_PIN   14  // WARNING
#define SPRINKLER_PIN  12  // Auto-sprinkler
#define EXHAUST_FAN_PIN 13 // Exhaust fan

// ── DHT22 & OLED ──────────────────────────────
#define DHT_TYPE     DHT22
DHT dht(DHT_PIN, DHT_TYPE);

#define SCREEN_WIDTH  128
#define SCREEN_HEIGHT 64
Adafruit_SSD1306 display(SCREEN_WIDTH, SCREEN_HEIGHT, &Wire, -1);

// ── Alert Levels ──────────────────────────────
enum AlertLevel { SAFE, WARNING, DANGER, CRITICAL };

// ── System State Struct ───────────────────────
struct SystemState {
  float temperature, humidity;
  int   smokeLevel, flameLevel;
  AlertLevel alertLevel;
  bool  sprinklerActive, exhaustFanActive, alarmActive;
  unsigned long lastAlert;
  int   alertCount;
  String location;
} fireSystem;

// ── Thresholds ────────────────────────────────
const float TEMP_WARNING  = 35.0;
const float TEMP_DANGER   = 45.0;
const float TEMP_CRITICAL = 55.0;
const int   SMOKE_WARNING  = 30;
const int   SMOKE_DANGER   = 50;
const int   SMOKE_CRITICAL = 70;
const int   FLAME_THRESHOLD = 40;

unsigned long lastSensorRead = 0, lastDisplayUpdate = 0, alarmStartTime = 0;
const long sensorInterval = 1000, displayInterval = 500;

// ── Alert History (rolling 10 entries) ────────
struct AlertLog { String timestamp, level; float temp; int smoke, flame; };
AlertLog alertHistory[10];
int historyIndex = 0;

sketch.ino — setup() & Core Functions

void setup() {
  Serial.begin(115200);
  pinMode(BUZZER_PIN,      OUTPUT);
  pinMode(RED_LED_PIN,     OUTPUT);
  pinMode(GREEN_LED_PIN,   OUTPUT);
  pinMode(BLUE_LED_PIN,    OUTPUT);
  pinMode(SPRINKLER_PIN,   OUTPUT);
  pinMode(EXHAUST_FAN_PIN, OUTPUT);
  pinMode(MQ2_PIN,   INPUT);
  pinMode(FLAME_PIN, INPUT);
  dht.begin();

  if (!display.begin(SSD1306_SWITCHCAPVCC, 0x3C)) {
    Serial.println(F("OLED failed"));
  } else {
    display.clearDisplay(); display.setTextSize(1);
    display.setTextColor(SSD1306_WHITE);
    display.setCursor(0,0); display.println("FIRE DETECTION");
    display.println("Initializing..."); display.display(); delay(2000);
  }

  fireSystem = {0,0,0,0,SAFE,false,false,false,0,0,"Building A - Floor 3"};

  WiFi.begin(ssid, password);
  while (WiFi.status() != WL_CONNECTED) { delay(500); }

  server.on("/",        handleRoot);
  server.on("/status",  handleStatus);
  server.on("/history", handleHistory);
  server.on("/reset",   handleReset);
  server.on("/test",    handleTest);
  server.on("/silence", handleSilence);
  server.begin();

  Serial.print("Dashboard: http://");
  Serial.println(WiFi.localIP());
  setStatusLED(SAFE);
  playStartupTone();
}

void loop() {
  server.handleClient();
  unsigned long now = millis();

  if (now - lastSensorRead >= sensorInterval) {
    lastSensorRead = now;
    readSensors(); evaluateFireRisk(); controlSafetySystems();
  }
  if (now - lastDisplayUpdate >= displayInterval) {
    lastDisplayUpdate = now; updateDisplay();
  }
  if (fireSystem.alarmActive) handleAlarm();
}

void readSensors() {
  fireSystem.temperature = dht.readTemperature();
  fireSystem.humidity    = dht.readHumidity();
  if (isnan(fireSystem.temperature)) fireSystem.temperature = 0;
  if (isnan(fireSystem.humidity))    fireSystem.humidity    = 0;

  int smokeRaw = analogRead(MQ2_PIN);
  int flameRaw = analogRead(FLAME_PIN);
  fireSystem.smokeLevel = map(smokeRaw, 0, 4095, 0,   100);
  fireSystem.flameLevel = map(flameRaw, 0, 4095, 100,   0); // Inverted
}

void evaluateFireRisk() {
  AlertLevel prev = fireSystem.alertLevel, next = SAFE;

  if (fireSystem.temperature >= TEMP_CRITICAL ||
      fireSystem.smokeLevel   >= SMOKE_CRITICAL ||
      fireSystem.flameLevel   >= FLAME_THRESHOLD) next = CRITICAL;
  else if (fireSystem.temperature >= TEMP_DANGER ||
           fireSystem.smokeLevel   >= SMOKE_DANGER)  next = DANGER;
  else if (fireSystem.temperature >= TEMP_WARNING ||
           fireSystem.smokeLevel   >= SMOKE_WARNING)  next = WARNING;

  fireSystem.alertLevel = next;
  if (next != prev) handleAlertChange(prev, next);
}

void handleAlertChange(AlertLevel old, AlertLevel n) {
  logAlert(); setStatusLED(n);
  if (n >= DANGER && old < DANGER) { activateAlarm(); sendAlert(); }
  if (n == SAFE  && old != SAFE)   deactivateAlarm();
}

void controlSafetySystems() {
  // Sprinkler — CRITICAL only
  if (fireSystem.alertLevel == CRITICAL && !fireSystem.sprinklerActive)
    activateSprinkler();
  else if (fireSystem.alertLevel < CRITICAL && fireSystem.sprinklerActive)
    deactivateSprinkler();
  // Exhaust fan — smoke >= 30%
  if (fireSystem.smokeLevel >= SMOKE_WARNING && !fireSystem.exhaustFanActive)
    activateExhaustFan();
  else if (fireSystem.smokeLevel < SMOKE_WARNING && fireSystem.exhaustFanActive)
    deactivateExhaustFan();
}

void handleAlarm() {
  unsigned long elapsed = millis() - alarmStartTime;
  int pattern = (elapsed / 200) % 4;
  if (fireSystem.alertLevel == CRITICAL)
    digitalWrite(BUZZER_PIN, pattern < 2 ? HIGH : LOW);
  else if (fireSystem.alertLevel == DANGER)
    digitalWrite(BUZZER_PIN, pattern < 1 ? HIGH : LOW);
}

void setStatusLED(AlertLevel level) {
  digitalWrite(RED_LED_PIN,   LOW);
  digitalWrite(GREEN_LED_PIN, LOW);
  digitalWrite(BLUE_LED_PIN,  LOW);
  switch(level) {
    case SAFE:     digitalWrite(GREEN_LED_PIN, HIGH); break;
    case WARNING:  digitalWrite(BLUE_LED_PIN,  HIGH); break;
    case DANGER:   digitalWrite(RED_LED_PIN,   HIGH); break;
    case CRITICAL: digitalWrite(RED_LED_PIN, (millis()/200)%2); break;
  }
}

void activateSprinkler()  { fireSystem.sprinklerActive = true;  digitalWrite(SPRINKLER_PIN, HIGH); Serial.println("SPRINKLER ON"); }
void deactivateSprinkler(){ fireSystem.sprinklerActive = false; digitalWrite(SPRINKLER_PIN, LOW);  Serial.println("Sprinkler OFF"); }
void activateExhaustFan() { fireSystem.exhaustFanActive = true;  digitalWrite(EXHAUST_FAN_PIN, HIGH); Serial.println("FAN ON"); }
void deactivateExhaustFan(){ fireSystem.exhaustFanActive = false; digitalWrite(EXHAUST_FAN_PIN, LOW);  Serial.println("Fan OFF"); }
void activateAlarm()   { fireSystem.alarmActive = true;  alarmStartTime = millis(); Serial.println("ALARM ON"); }
void deactivateAlarm() { fireSystem.alarmActive = false; digitalWrite(BUZZER_PIN, LOW);  Serial.println("Alarm OFF"); }

void playStartupTone() {
  tone(BUZZER_PIN, 1000, 100); delay(150);
  tone(BUZZER_PIN, 1500, 100); delay(150);
  tone(BUZZER_PIN, 2000, 100);
}

String getAlertLevelName(AlertLevel level) {
  switch(level) {
    case SAFE:     return "SAFE";
    case WARNING:  return "WARNING";
    case DANGER:   return "DANGER";
    case CRITICAL: return "CRITICAL";
    default:       return "UNKNOWN";
  }
}

void updateDisplay() {
  display.clearDisplay(); display.setCursor(0,0);
  display.println("FIRE DETECTION");
  display.drawLine(0,9,128,9,SSD1306_WHITE);
  display.setCursor(0,12); display.print("Status: "); display.println(getAlertLevelName(fireSystem.alertLevel));
  display.setCursor(0,22); display.print("Temp: "); display.print(fireSystem.temperature,1); display.println(" C");
  display.setCursor(0,32); display.print("Smoke: "); display.print(fireSystem.smokeLevel); display.println(" %");
  display.setCursor(0,42); display.print("Flame: "); display.print(fireSystem.flameLevel); display.println(" %");
  display.setCursor(0,52);
  if(fireSystem.sprinklerActive)  display.print("SPRINKLER ");
  if(fireSystem.exhaustFanActive) display.print("FAN ");
  if(fireSystem.alarmActive)      display.print("ALARM");
  display.display();
}

void logAlert() {
  alertHistory[historyIndex] = {
    String(millis()/1000) + "s",
    getAlertLevelName(fireSystem.alertLevel),
    fireSystem.temperature, fireSystem.smokeLevel, fireSystem.flameLevel
  };
  historyIndex = (historyIndex + 1) % 10;
}

void sendAlert() {
  fireSystem.alertCount++;
  Serial.println("EMERGENCY ALERT SENT — Level: " + getAlertLevelName(fireSystem.alertLevel));
}

// ── Web Server Handlers (handleRoot, handleStatus, etc.)
// Full web dashboard code included in the Wokwi simulation link above ──
void handleReset()   { fireSystem.alertCount=0; fireSystem.alarmActive=false; historyIndex=0; server.sendHeader("Location","/"); server.send(303); }
void handleSilence() { fireSystem.alarmActive=false; digitalWrite(BUZZER_PIN,LOW); server.sendHeader("Location","/"); server.send(303); }
void handleTest()    { for(int i=0;i<3;i++){tone(BUZZER_PIN,2000,200);delay(300);} server.sendHeader("Location","/"); server.send(303); }
void handleStatus()  { /* Returns JSON — see Wokwi simulation for full implementation */ }
void handleHistory() { /* Returns JSON history — see Wokwi simulation for full implementation */ }
void handleRoot()    { /* Returns full HTML dashboard — see Wokwi simulation */ }

ℹ️ The web dashboard handleRoot() function generates full HTML with CSS and sensor data. The complete implementation is in the Wokwi simulation — open it here to see and copy the full code.

06 · Wokwi Circuit File

diagram.json — One-Click Circuit Setup

Paste this into the diagram.json tab in Wokwi to automatically place and wire all components.

⚠️ Copy the entire JSON — starts with { and ends with }. In Wokwi, click the diagram.json tab → Ctrl+A → Delete → Paste → Ctrl+S.

diagram.json — IoT Fire Detection System

{
  "version": 1,
  "author": "IoT Fire Detection System",
  "editor": "wokwi",
  "parts": [
    { "type": "wokwi-esp32-devkit-v1", "id": "esp",      "top": 0,      "left": 0,     "attrs": {} },
    { "type": "wokwi-dht22",           "id": "dht1",     "top": -86.4,  "left": 124.8, "attrs": { "temperature": "30", "humidity": "50" } },
    { "type": "wokwi-potentiometer",   "id": "smoke",    "top": -19.2,  "left": 297.6, "rotate": 180, "attrs": { "label": "Smoke Sensor (MQ-2)" } },
    { "type": "wokwi-potentiometer",   "id": "flame",    "top": 86.4,   "left": 297.6, "rotate": 180, "attrs": { "label": "Flame Sensor" } },
    { "type": "wokwi-led",             "id": "red_led",  "top": -124.8, "left": 422.4, "attrs": { "color": "red",   "lightColor": "red",   "label": "DANGER" } },
    { "type": "wokwi-resistor",        "id": "r1",       "top": -67.2,  "left": 422.4, "rotate": 90,  "attrs": { "value": "220" } },
    { "type": "wokwi-led",             "id": "green_led","top": -124.8, "left": 499.2, "attrs": { "color": "green", "lightColor": "green", "label": "SAFE" } },
    { "type": "wokwi-resistor",        "id": "r2",       "top": -67.2,  "left": 499.2, "rotate": 90,  "attrs": { "value": "220" } },
    { "type": "wokwi-led",             "id": "blue_led", "top": -124.8, "left": 576,   "attrs": { "color": "blue",  "lightColor": "blue",  "label": "WARNING" } },
    { "type": "wokwi-resistor",        "id": "r3",       "top": -67.2,  "left": 576,   "rotate": 90,  "attrs": { "value": "220" } },
    { "type": "wokwi-led",             "id": "sprinkler","top": 38.4,   "left": 422.4, "attrs": { "color": "cyan",  "lightColor": "cyan",  "label": "Sprinkler" } },
    { "type": "wokwi-resistor",        "id": "r4",       "top": 96,     "left": 422.4, "rotate": 90,  "attrs": { "value": "220" } },
    { "type": "wokwi-led",             "id": "fan",      "top": 38.4,   "left": 499.2, "attrs": { "color": "white", "lightColor": "white", "label": "Exhaust Fan" } },
    { "type": "wokwi-resistor",        "id": "r5",       "top": 96,     "left": 499.2, "rotate": 90,  "attrs": { "value": "220" } },
    { "type": "wokwi-buzzer",          "id": "bz1",      "top": 172.8,  "left": 470.4, "attrs": { "volume": "0.5" } },
    { "type": "wokwi-ssd1306",         "id": "oled1",    "top": 192,    "left": 249.6, "attrs": { "i2cAddress": "0x3C" } }
  ],
  "connections": [
    [ "esp:TX0",        "$serialMonitor:RX", "",       [] ],
    [ "esp:RX0",        "$serialMonitor:TX", "",       [] ],
    [ "dht1:VCC",       "esp:3V3",    "red",    ["v0"] ],
    [ "dht1:GND",       "esp:GND.1",  "black",  ["v0"] ],
    [ "dht1:SDA",       "esp:D15",    "green",  ["v0"] ],
    [ "smoke:GND",      "esp:GND.1",  "black",  ["v0"] ],
    [ "smoke:VCC",      "esp:3V3",    "red",    ["v0"] ],
    [ "smoke:SIG",      "esp:D34",    "orange", ["v0"] ],
    [ "flame:GND",      "esp:GND.2",  "black",  ["v0"] ],
    [ "flame:VCC",      "esp:3V3",    "red",    ["v0"] ],
    [ "flame:SIG",      "esp:D35",    "yellow", ["v0"] ],
    [ "red_led:A",      "esp:D26",    "red",    ["v0"] ],
    [ "red_led:C",      "r1:1",       "red",    ["v0"] ],
    [ "r1:2",           "esp:GND.1",  "black",  ["v0"] ],
    [ "green_led:A",    "esp:D27",    "green",  ["v0"] ],
    [ "green_led:C",    "r2:1",       "green",  ["v0"] ],
    [ "r2:2",           "esp:GND.1",  "black",  ["v0"] ],
    [ "blue_led:A",     "esp:D14",    "blue",   ["v0"] ],
    [ "blue_led:C",     "r3:1",       "blue",   ["v0"] ],
    [ "r3:2",           "esp:GND.1",  "black",  ["v0"] ],
    [ "sprinkler:A",    "esp:D12",    "cyan",   ["v0"] ],
    [ "sprinkler:C",    "r4:1",       "cyan",   ["v0"] ],
    [ "r4:2",           "esp:GND.2",  "black",  ["v0"] ],
    [ "fan:A",          "esp:D13",    "white",  ["v0"] ],
    [ "fan:C",          "r5:1",       "white",  ["v0"] ],
    [ "r5:2",           "esp:GND.2",  "black",  ["v0"] ],
    [ "bz1:1",          "esp:D25",    "purple", ["v0"] ],
    [ "bz1:2",          "esp:GND.2",  "black",  ["v0"] ],
    [ "oled1:VCC",      "esp:3V3",    "red",    ["h0"] ],
    [ "oled1:GND",      "esp:GND.2",  "black",  ["h0"] ],
    [ "oled1:SDA",      "esp:D21",    "blue",   ["h0"] ],
    [ "oled1:SCL",      "esp:D22",    "yellow", ["h0"] ]
  ],
  "dependencies": {}
}

07 · Web Dashboard

Live Web Dashboard Preview

Once the simulation connects to WiFi, open the IP address shown in the Serial Monitor to access the live dashboard from any browser.

🚨 Fire Detection System

Building A - Floor 3

🌡️ Temperature

30.0°C

💨 Smoke Level

🔥 Flame

💧 Humidity

50%

🚿 Sprinkler System Standby

💨 Exhaust Fan Standby

🔔 Alarm System Silent

Auto-refreshes every 2 seconds · Mobile responsive · Remote controls available

💡 The dashboard also exposes a /status JSON endpoint and /history log — useful for integrating with MQTT, Node-RED, or Home Assistant in a real deployment.

08 · How to Test

Simulate a Fire — Step by Step

Follow these 4 steps in order to experience the full escalation from SAFE to CRITICAL alert.

Step 1

🟢 Normal Conditions

Start simulation — click ▶ Play
Green LED lights up (SAFE)
No alarm, all systems standby
OLED shows temperature and "SAFE"

Step 2

🔵 Raise Temperature

Click the DHT22 sensor in Wokwi
Drag temperature slider to 40°C
Blue LED lights up (WARNING)
No alarm yet — monitor mode

Step 3

🔴 Add Smoke

Rotate Smoke Sensor dial to ~60%
Red LED lights up (DANGER)
Alarm beeps in medium pattern
Exhaust fan LED turns ON 💨
Alert notification logged

Step 4

🚨 Detect Flames

Rotate Flame Sensor dial to ~50%
Red LED flashes rapidly (CRITICAL)
Alarm beeps continuously
Cyan LED = Sprinkler active 🚿
Emergency alerts sent!

🚨 To silence the alarm, click the Silence Alarm button on the web dashboard, or reduce all sensor readings back to safe levels. The system automatically de-escalates when all sensors drop below thresholds.

09 · More Projects

All ESP32 Projects on MakeMindz

⚡ ESP32 IoT Projects

Smart Home Automation IoT Weather Station ESP32 Web Server MQTT Weather Logger ESP32-CAM Security Camera Smart Irrigation System Voice-Controlled Assistant IoT Energy Monitor Smart Parking System Gas Leak Detection Smart Doorbell ✓ IoT Fire Detection OLED with ESP32 ESP32 Ultrasonic Distance Meter BLE Beacon System

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🟡 Advanced Arduino Projects

Password-Based Lock RFID Access Control Biometric Access Multi-Sensor Weather Station ColorChord Musical Sequencer

IoT-Based Fire Detection & Alert System using ESP 32

What You'll Build

Triple Sensor

4-Level Alerts

Auto-Sprinkler

Exhaust Fan

Web Dashboard

Alert Simulation

OLED Display

Data Logging

Components Required

4-Level Alert System

Sensor Thresholds

Pin Connections

Complete Setup Guide

🌐 Open Wokwi & Start a New ESP32 Project

📋 Paste the diagram.json — Auto-Wire in One Click

📚 Install Required Libraries

💻 Paste the Arduino Code

🔗 Use the Pre-Built Simulation

Open Complete Fire Detection Simulation

The Complete Sketch

diagram.json — One-Click Circuit Setup

Live Web Dashboard Preview

Simulate a Fire — Step by Step

🟢 Normal Conditions

🔵 Raise Temperature

🔴 Add Smoke

🚨 Detect Flames

All ESP32 Projects on MakeMindz

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