IoT Home Defense System

A Raspberry Pi-based security system featuring motion detection, RFID authentication, real-time monitoring, and automated alerts with MQTT integration.

Team Members

Nathan Roos
Louis Caron

System Overview

This IoT home defense system provides comprehensive security monitoring with the following features:

Motion Detection: PIR sensor monitors for unauthorized movement
RFID Authentication: Secure arm/disarm using RFID key cards
Visual Indicators: Three-LED system (Green/Yellow/Red) shows system state
Audio Alerts: Buzzer provides warning beeps and alarm sounds
LCD Display: 16x2 character display shows countdown timers and temperature
Camera Integration: Captures photos on disarm and records video during alerts
Environmental Monitoring: DHT11 sensor tracks temperature
MQTT Integration: Real-time status updates to cloud dashboard
Data Logging: CSV logging of all system events

System States

DISARMED (Green LED): System idle, displays time and temperature
ARMING (Yellow LED blinking): 15-second countdown with warning beeps
ARMED (Red LED): Motion detection active
DISARMING (Yellow LED blinking): User has limited time to present RFID key
ALERT (Red LED blinking): Alarm triggered, recording video

Block Diagram

┌─────────────────────────────────────────────────────────────────┐
│                      Raspberry Pi 4                              │
│                                                                   │
│  ┌──────────────┐      ┌──────────────┐      ┌──────────────┐  │
│  │   Main       │      │   MQTT       │      │   Camera     │  │
│  │   Controller │◄────►│   Client     │      │   Module     │  │
│  │   (main.py)  │      │              │      │   (Pi Cam)   │  │
│  └──────┬───────┘      └──────────────┘      └──────┬───────┘  │
│         │                                             │           │
│         ├─────────────────────────────────────────────┤           │
│         │                                             │           │
└─────────┼─────────────────────────────────────────────┼───────────┘
          │                                             │
    ┌─────┴─────────────────────────────────────────────┴─────┐
    │                                                           │
    ▼                                                           ▼
┌────────┐  ┌────────┐  ┌────────┐  ┌────────┐  ┌────────┐  ┌────────┐
│  PIR   │  │  RFID  │  │ Button │  │ Buzzer │  │  LEDs  │  │  LCD   │
│ Motion │  │ RC522  │  │        │  │        │  │  x3    │  │ 16x2   │
│ Sensor │  │ Reader │  │        │  │        │  │        │  │        │
└────────┘  └────────┘  └────────┘  └────────┘  └────────┘  └────────┘
    │           │           │           │           │           │
    └───────────┴───────────┴───────────┴───────────┴───────────┘
                          GPIO Interface

Bill of Materials

Component	Model	Quantity	Link
Microcontroller	Raspberry Pi 4 Model B (4GB)	1	Adafruit
Camera	Raspberry Pi Camera Module V2	1	Adafruit
Motion Sensor	HC-SR501 PIR Motion Sensor	1	Amazon
RFID Reader	MFRC522 RFID Module	1	Amazon
Temperature Sensor	DHT11 Temperature & Humidity Sensor	1	Adafruit
Display	16x2 Character LCD (HD44780)	1	Adafruit
LEDs	5mm LEDs (Red, Yellow, Green)	3	Amazon
Buzzer	Active Buzzer 5V	1	Amazon
Push Button	Tactile Push Button 12mm	1	Adafruit
Resistors	220Ω Resistors (for LEDs)	3	Amazon
Breadboard	830 Point Solderless Breadboard	1	Adafruit
Jumper Wires	Male-to-Male/Male-to-Female	1 set	Amazon
Power Supply	5V 3A USB-C Power Supply	1	Adafruit
MicroSD Card	32GB MicroSD Card Class 10	1	Amazon

Estimated Total Cost: ~$150-200 USD

Wiring Diagram

GPIO Pin Assignments

Component	GPIO Pin	Physical Pin	Notes
PIR Motion Sensor	GPIO 4	Pin 7	Signal output
DHT11 Sensor	GPIO 5	Pin 29	Data line
LCD RS	GPIO 23	Pin 16	Register select
LCD Enable	GPIO 24	Pin 18	Enable signal
LCD D4	GPIO 6	Pin 31	Data bit 4
LCD D5	GPIO 13	Pin 33	Data bit 5
LCD D6	GPIO 19	Pin 35	Data bit 6
LCD D7	GPIO 26	Pin 37	Data bit 7
Button	GPIO 12	Pin 32	Pull-up resistor
Buzzer	GPIO 18	Pin 12	PWM capable
Green LED	GPIO 16	Pin 36	Via 220Ω resistor
Yellow LED	GPIO 20	Pin 38	Via 220Ω resistor
Red LED	GPIO 21	Pin 40	Via 220Ω resistor
RFID SDA	GPIO 8 (CE0)	Pin 24	SPI chip select
RFID SCK	GPIO 11 (SCLK)	Pin 23	SPI clock
RFID MOSI	GPIO 10 (MOSI)	Pin 19	SPI data out
RFID MISO	GPIO 9 (MISO)	Pin 21	SPI data in
RFID RST	GPIO 25	Pin 22	Reset (optional)

Schematic Diagram

                    Raspberry Pi 4
                    ┌────────────┐
                    │            │
    PIR ────────────┤ GPIO 4     │
    DHT11 ──────────┤ GPIO 5     │
                    │            │
    Button ─────────┤ GPIO 12    │
    Buzzer ─────────┤ GPIO 18    │
                    │            │
    Green LED ──────┤ GPIO 16    │
    Yellow LED ─────┤ GPIO 20    │
    Red LED ────────┤ GPIO 21    │
                    │            │
    LCD RS ─────────┤ GPIO 23    │
    LCD EN ─────────┤ GPIO 24    │
    LCD D4 ─────────┤ GPIO 6     │
    LCD D5 ─────────┤ GPIO 13    │
    LCD D6 ─────────┤ GPIO 19    │
    LCD D7 ─────────┤ GPIO 26    │
                    │            │
    RFID SDA ───────┤ GPIO 8     │
    RFID SCK ───────┤ GPIO 11    │
    RFID MOSI ──────┤ GPIO 10    │
    RFID MISO ──────┤ GPIO 9     │
    RFID RST ───────┤ GPIO 25    │
                    │            │
    Camera ─────────┤ CSI Port   │
                    │            │
    GND ────────────┤ GND        │
    5V ─────────────┤ 5V         │
    3.3V ───────────┤ 3.3V       │
                    └────────────┘

LED Connections (each):
GPIO Pin ──── 220Ω Resistor ──── LED Anode ──── Cathode ──── GND

Button Connection:
GPIO 12 ──── Button ──── GND (Internal pull-up enabled)

Photos

Setup Instructions

1. Operating System Preparation

# Flash Raspberry Pi OS (64-bit) to microSD card using Raspberry Pi Imager
# Boot the Pi and run initial updates
sudo apt update && sudo apt upgrade -y

# Enable required interfaces
sudo raspi-config
# Navigate to: Interface Options
# Enable: Camera, SPI, I2C

# Reboot to apply changes
sudo reboot

2. Install System Dependencies

# Install Python 3 and pip
sudo apt install python3 python3-pip python3-venv -y

# Install system libraries
sudo apt install libgpiod2 python3-libgpiod -y
sudo apt install python3-picamera2 -y
sudo apt install libcap-dev -y

# Install SPI and I2C tools
sudo apt install python3-spidev python3-smbus i2c-tools -y

# Install OpenCV dependencies
sudo apt install libatlas-base-dev libhdf5-dev libhdf5-serial-dev libjasper-dev libqtgui4 libqt4-test -y

3. Project Setup

# Clone the repository
git clone https://github.com/yourusername/iot-home-defense-system.git
cd iot-home-defense-system

# Create virtual environment
python3 -m venv venv
source venv/bin/activate

# Install Python dependencies
pip install -r requirements.txt

4. Install Python Dependencies

Create a requirements.txt file:

python-dotenv==1.0.0
paho-mqtt==1.6.1
adafruit-circuitpython-dht==3.7.8
adafruit-circuitpython-charlcd==3.4.5
picamera2==0.3.12
opencv-python==4.8.1.78
spidev==3.6
mfrc522==0.0.7

Install:

pip install -r requirements.txt

5. Environment Variables

Create a .env file in the project root:

# LED Configuration
LED_BLINK_INTERVAL=0.5

# Timing Configuration (seconds)
DETECTION_DELAY=10
ALARM_DELAY=15

# MQTT Configuration
MQTT_HOST=io.adafruit.com
MQTT_PORT=1883
MQTT_TIMEOUT=60
MQTT_USERNAME=your_adafruit_username
MQTT_KEY=your_adafruit_io_key
TOPICS=alarm-status,temperature

# Camera Configuration
IMAGE_LOCATION=/home/pi/alarm_images

6. Create Required Directories

# Create image storage directory
mkdir -p /home/pi/alarm_images
chmod 755 /home/pi/alarm_images

# Create log directory
mkdir -p /home/pi/alarm_system/logs

7. Configure RFID Keys

# Run the RFID enrollment script
python3 utils/enroll_rfid.py

# Follow prompts to scan and register authorized RFID cards

How to Run

Manual Execution

# Activate virtual environment
source venv/bin/activate

# Run the main program
python3 main.py

Run as System Service

Create a systemd service file:

sudo nano /etc/systemd/system/alarm-system.service

Add the following content:

[Unit]
Description=IoT Home Defense Alarm System
After=network.target

[Service]
Type=simple
User=pi
WorkingDirectory=/home/pi/iot-home-defense-system
Environment="PATH=/home/pi/iot-home-defense-system/venv/bin"
ExecStart=/home/pi/iot-home-defense-system/venv/bin/python3 main.py
Restart=on-failure
RestartSec=10

[Install]
WantedBy=multi-user.target

Enable and start the service:

# Reload systemd
sudo systemctl daemon-reload

# Enable service to start on boot
sudo systemctl enable alarm-system.service

# Start the service
sudo systemctl start alarm-system.service

# Check status
sudo systemctl status alarm-system.service

# View logs
journalctl -u alarm-system.service -f

Dashboard Access

Adafruit IO Dashboard: https://io.adafruit.com/{your_username}/dashboards

Create feeds for:

alarm-status: Displays current system state
temperature: Shows real-time temperature readings

CLI Commands

# Start the system
sudo systemctl start alarm-system.service

# Stop the system
sudo systemctl stop alarm-system.service

# Restart the system
sudo systemctl restart alarm-system.service

# View real-time logs
journalctl -u alarm-system.service -f

# View recent logs
journalctl -u alarm-system.service -n 100

# Check system status
sudo systemctl status alarm-system.service

Data Format Specification

CSV Log Files

The system generates two CSV files for data logging:

1. `alarm-status.csv`

Records all system state changes.

Fields:

timestamp (ISO 8601 format): Date and time of state change
message (string): System state value

States:

disarmed: System inactive
arming: Countdown active
armed: Motion detection enabled
disarming: User authentication in progress
alert: Alarm triggered

Example:

timestamp,message
2025-11-04T14:23:15.123456,disarmed
2025-11-04T14:25:30.654321,arming
2025-11-04T14:25:45.789012,armed
2025-11-04T14:30:12.345678,disarming
2025-11-04T14:30:15.901234,alert

2. `temperature.csv`

Records temperature readings from DHT11 sensor.

Fields:

timestamp (ISO 8601 format): Date and time of reading
message (float): Temperature in Celsius

Units: Degrees Celsius (°C)

Example:

timestamp,message
2025-11-04T14:23:15.123456,22.0
2025-11-04T14:23:20.234567,22.5
2025-11-04T14:23:25.345678,23.0

Image/Video Files

Photo Naming Convention:

disarmed_YYYYMMDD_HHMMSS.jpg

Captured when system is successfully disarmed
Stores in /home/pi/alarm_images/

Video Naming Convention:

alert_YYYYMMDD_HHMMSS.mp4

Recorded during alert state
Continues until system is disarmed
Stores in /home/pi/alarm_images/

File Rotation Policy

CSV Files:

No automatic rotation implemented
Manual archival recommended monthly
Suggested script for monthly rotation:

#!/bin/bash
# Add to crontab: 0 0 1 * * /home/pi/rotate_logs.sh

DATE=$(date +%Y%m)
cd /home/pi/iot-home-defense-system

# Archive CSV files
mkdir -p archives/$DATE
mv alarm-status.csv archives/$DATE/alarm-status-$DATE.csv
mv temperature.csv archives/$DATE/temperature-$DATE.csv

# Compress archives older than 3 months
find archives/* -type d -mtime +90 -exec tar -czf {}.tar.gz {} \; -exec rm -rf {} \;

Media Files:

Images and videos accumulate in /home/pi/alarm_images/
Recommended: Review and archive weekly
Suggested cleanup for files older than 30 days:

# Delete media files older than 30 days
find /home/pi/alarm_images -type f -mtime +30 -delete

Known Limitations

Hardware Limitations

PIR Sensor Sensitivity
- Fixed detection range (~7 meters)
- Cannot distinguish between authorized and unauthorized movement
- Sensitive to temperature changes and small animals
- 2-second minimum interval between detections
DHT11 Accuracy
- Temperature accuracy: ±2°C
- Humidity not currently utilized
- Slow response time (~2 seconds per reading)
Camera Module
- Requires adequate lighting for quality capture
- Fixed position limits coverage area
- Video files can be large (no compression implemented)
RFID Reader
- Limited read range (~3-5cm)
- Only supports MIFARE Classic cards
- No encryption on stored card IDs

Software Limitations

Single User Authentication
- No multi-user support
- All authorized RFID cards have equal access
- No logging of which specific card was used
Network Dependency
- MQTT failures don't prevent local operation but lose remote monitoring
- No automatic reconnection with exponential backoff
- No offline queueing of messages
Error Handling
- Limited recovery from hardware disconnections
- Camera failures don't gracefully degrade
- No watchdog timer for system hangs
Storage Management
- No automatic cleanup of old images/videos
- CSV files grow indefinitely
- No disk space monitoring
Security Concerns
- MQTT credentials stored in plaintext .env file
- RFID card IDs not encrypted
- No tamper detection on physical components
- Camera images not encrypted at rest

Future Work

Short-term Enhancements (1-3 months)

Improved Authentication
- Multi-user RFID support with individual codes
- PIN pad backup authentication method
- Logging of specific user access events
- Duress code feature to silently alert authorities
Enhanced Monitoring
- Web dashboard for real-time status
- Mobile app notifications via MQTT/push services
- Email alerts with attached photos
- SMS alerts for critical events
Better Error Handling
- Automatic MQTT reconnection with exponential backoff
- Graceful degradation when components fail
- Hardware watchdog timer integration
- Self-diagnostic on startup
Storage Management
- Automatic file rotation and archiving
- Disk space monitoring with alerts
- Video compression to reduce storage
- Cloud backup integration (AWS S3, Google Drive)

Medium-term Goals (3-6 months)

AI/ML Integration
- Person detection using TensorFlow Lite
- Facial recognition for known individuals
- Anomaly detection in motion patterns
- False alarm reduction through learning
Multiple Zones
- Support for multiple PIR sensors
- Zone-based arming (e.g., perimeter only)
- Different alert levels per zone
- Chaining multiple Raspberry Pis
Advanced Camera Features
- Pan-tilt mechanism for wider coverage
- Night vision using IR camera
- Motion-based tracking
- Time-lapse recording
Enhanced Security
- Encrypted MQTT communication (TLS)
- Encrypted storage of credentials
- Hardware security module (HSM) for key storage
- Tamper detection on enclosure

Long-term Vision (6-12 months)

Professional Features
- Integration with professional monitoring services
- Z-Wave/Zigbee integration for smart home
- Voice control via Alexa/Google Assistant
- Geofencing for automatic arm/disarm
Distributed System
- Multi-location support with central dashboard
- Peer-to-peer alerting between systems
- Mesh network for sensor communication
- Edge computing for local AI processing
Compliance & Standards
- UL/CE certification for alarm systems
- GDPR compliance for data storage
- AES-256 encryption throughout
- Professional installer mode
Business Model
- Subscription service for cloud features
- Professional installation option
- Insurance integration for discounts
- Open API for third-party integrations

Troubleshooting

Common Issues

System won't start:

# Check service status
sudo systemctl status alarm-system.service

# Check for Python errors
python3 main.py

# Verify GPIO permissions
sudo usermod -a -G gpio,spi,i2c pi

RFID not reading:

# Test SPI interface
ls -l /dev/spidev*

# Check connections
python3 -c "from mfrc522 import SimpleMFRC522; reader = SimpleMFRC522(); print('Place card...'); print(reader.read())"

Camera not working:

# Test camera
libcamera-still -o test.jpg

# Check camera enabled
sudo raspi-config

Link to Deployed Flask App

https://iot-project-flask-4.onrender.com

MQTT not connecting:

Verify credentials in .env
Check network connectivity: ping io.adafruit.com
Review firewall rules

Contributing

Contributions are welcome! Please:

Fork the repository
Create a feature branch
Submit a pull request with detailed description

Project Reflection

Our IoT Home Automation and Security System successfully integrates hardware sensors (DHT11 temperature/humidity, PIR motion, camera module) with cloud services through Adafruit IO MQTT and a PostgreSQL database hosted on Neon.tech. The Flask web interface provides real-time monitoring of environmental conditions, wireless device control for six connected components, and historical data visualization through interactive Chart.js bar charts showing daily averages and alert counts. What worked exceptionally well was the MQTT communication protocol between the Raspberry Pi and Adafruit IO, allowing seamless bidirectional device control and data streaming with minimal latency. The hardest challenges were managing the integration between multiple cloud services—coordinating Raspberry Pi sensor data collection, Adafruit IO feed synchronization, PostgreSQL database queries, and Flask API endpoints required extensive debugging of connection timeouts, authentication issues, and data format mismatches across different systems. Database deployment on Render.com initially posed significant challenges with psycopg library version compatibility between Python 3.13 and PostgreSQL, table schema creation timing, and environment variable configuration for secure credential management. The system architecture evolved from direct psycopg connections to considering Neon's REST API for better serverless deployment compatibility. If we had more time, we would implement OAuth2 user authentication for multi-user access with role-based permissions, develop more sophisticated predictive analytics using machine learning to identify temperature/humidity patterns and forecast anomalies, create a Progressive Web App (PWA) for native mobile experience with offline capabilities, integrate facial recognition using the camera module for authorized user identification instead of relying solely on RFID authentication, and add SMS notifications as an additional alert channel for critical security events. Overall, the project successfully demonstrates comprehensive end-to-end IoT system development spanning embedded hardware programming, real-time data streaming, cloud database management, REST API design, and responsive web interface development.

License

This project is licensed under the MIT License - see LICENSE file for details.

Acknowledgments

Adafruit for CircuitPython libraries and tutorials
Raspberry Pi Foundation for hardware documentation
MFRC522 library contributors
IoT community for inspiration and support

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