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Embedded Disaster Alert System — Fire & Earthquake Simulator

A distributed embedded system designed to simulate and detect earthquake and fire events in real time. Five microcontrollers communicate over serial links to handle sensor acquisition, physical actuation, GSM SMS alerting, and IoT telemetry simultaneously — all coordinated by a central Arduino Mega controller.

Demo

Fire Simulation

https://youtu.be/gObH_3M5nrk?si=5tWtFOhanTaUil6P

Earthquake Simulation

https://youtu.be/bN8KYFFl7Zw?si=bD3d5yVtjDiuSPyW

System Architecture

+------------------------------------+
|     Mobile App (Firebase RTDB)     |
+------------------------------------+
                  |
               [Wi-Fi]
                  |
          +-------+--------+
          |   ESP32         |<---- ThingSpeak
          |   (IoT Bridge)  |
          +-------+---------+
                  |
              [UART Serial]
                  |
    +-------------+-----------------+
    |  Arduino Mega - Main Controller|
    |  LCD | Relays | Lights | Audio |
    +---+-------------------+--------+
        |                   |
     [UART]              [UART]
        |                   |
+-------+------+   +--------+---------------+
| Arduino Uno  |   | Arduino Mega           |
| Fire Sensors |   | Earthquake Simulator   |
| 5x IR Flame  |   | ADXL335 + DC Motor     |
+--------------+   +------------------------+
                            |
                    +-------+----------+
                    | ESP8266 NodeMCU  |
                    | GSM SMS (SIM900A)|
                    +------------------+

Communication Flow

  • ESP32 → Main Mega: Mode commands, phone number, intensity level (UART)
  • Main Mega → Uno: Fire poll (UART Serial1)
  • Main Mega ↔ Earthquake Mega: Intensity commands + accelerometer readings (UART Serial2)
  • Main Mega → ESP8266: Fire/earthquake state for SMS dispatch (SoftwareSerial)
  • Main Mega → ESP32: Live sensor values for Firebase/ThingSpeak upload (UART Serial3)

Repository Structure

Embedded-Disaster-Alert-System-Fire-Earthquake-Simulator/
├── mega_receiver/
│   └── mega_receiver.ino       # Main controller — relay logic, LCD, serial hub
├── mega_earthquake/
│   └── mega_earthquake.ino     # Accelerometer reading + motor PWM control
├── uno_fire_sensor/
│   └── uno_fire_sensor.ino     # IR flame sensor acquisition + hold timer logic
├── esp8266_sms/
│   └── esp8266_sms.ino         # GSM SMS dispatch with deduplication
├── esp32_iot/
│   └── esp32_iot.ino           # Firebase RTDB polling + ThingSpeak telemetry
└── README.md

Hardware

Component Qty Role
Arduino Mega 2560 2 Main controller + Earthquake simulator
Arduino Uno 1 Fire sensor acquisition node
ESP32 1 IoT bridge — Firebase + ThingSpeak
ESP8266 NodeMCU 1 GSM SMS notification gateway
ADXL335 Accelerometer 1 3-axis vibration sensing
IR Flame Sensor 5 Per-zone fire detection (4 floors + house)
SIM900A GSM Module 1 SMS alert delivery
16x2 I2C LCD 1 Real-time system status display
DC Motor + L298N Driver 1 Physical earthquake shaking table
Relay Modules 9 Fan zones, alarm lights, speaker switching

Design Decisions

Single-character serial delimiters instead of JSON The Arduino Uno has only 2KB of SRAM. Using a lightweight delimiter-based protocol (e.g. 1A0B1C0D0E\n) over JSON keeps parsing fast and avoids heap fragmentation on constrained devices.

Zone fingerprint for SMS deduplication Rather than sending an SMS on every loop iteration that detects fire, the ESP8266 computes a numeric fingerprint of the active zone combination (fire1 + fire2×10 + fire3×100...). An SMS is only dispatched when the fingerprint changes — preventing alert spam during sustained detections.

Richter-scale intensity mapping from acceleration magnitude The ADXL335 outputs raw analog values. The earthquake Mega computes a 2D acceleration magnitude (√(ΔX² + ΔY²)) and maps it to a Richter-scale range (3.0–9.0) using linearly interpolated bands calibrated against a baseline average taken at startup.

Hold timer on fire sensors IR flame sensors can produce brief drop-outs in real flame conditions. A cycle-based hold timer keeps a zone flagged as active for a configurable window after the sensor clears — reducing false all-clear signals during active fires.

Startup motor burst on new intensity When the commanded earthquake intensity changes, the motor runs at full speed for 3 seconds before settling to the target PWM level. This overcomes the motor's static friction and ensures consistent startup behavior across all intensity levels.

Intensity to PWM Mapping

Richter Intensity PWM Value Motor Behavior
4 36 Mild vibration
5 47 Moderate vibration
6 92 Strong vibration
7 142 Very strong
8 225 Severe
0 0 Motor off

SMS Alert Examples

Fire (dynamic zone list):

Warning: Fire is detected on Second Floor and Fourth Floor.
Please stay calm and evacuate the premises immediately.

Earthquake:

Warning! Intensity 6.42 earthquake has been detected.

Setup & Deployment

1. Install Libraries

In Arduino IDE → Sketch → Include Library → Manage Libraries:

  • LiquidCrystal I2C by Frank de Brabander
  • FirebaseESP32 by Mobizt
  • ThingSpeak by MathWorks

2. Configure Credentials

Open esp32_iot/esp32_iot.ino and fill in your credentials:

#define WIFI_SSID       "YOUR_WIFI_SSID"
#define WIFI_PASSWORD   "YOUR_WIFI_PASSWORD"
#define FIREBASE_HOST   "https://YOUR_PROJECT_ID-default-rtdb.firebaseio.com/"
#define FIREBASE_AUTH   "YOUR_FIREBASE_SECRET_KEY"

3. Flash Each Board

Sketch Target Board Notes
mega_receiver.ino Arduino Mega Flash first
mega_earthquake.ino Arduino Mega Keep powered during calibration
uno_fire_sensor.ino Arduino Uno —
esp8266_sms.ino ESP8266 NodeMCU Ensure SIM card is inserted
esp32_iot.ino ESP32 Flash last after Wi-Fi credentials set

4. Power-On Sequence

  1. Arduino Uno (fire sensors)
  2. Arduino Mega — Earthquake
  3. Arduino Mega — Main Controller
  4. ESP8266
  5. ESP32

Known Issues / Limitations

  • SoftwareSerial on the ESP8266 can miss bytes at higher baud rates — keep all ports at 9600 baud
  • ThingSpeak free tier enforces a 15-second minimum between updates; the 3-second interval in the code will result in throttled uploads on free accounts
  • ADXL335 calibration is done at boot — ensure the hardware is completely stationary during the 3-second startup window

Author

Mark Anthony A. Lim LinkedIn [GitHub] (https://github.com/MarkLim15)