Distributed IOT Swarm Sensor Network

An IoT swarm system built with Raspberry Pi 5 and 3× ESP32 units that compete in real-time to become the "Master" based on ambient light intensity. The system features live web visualization via Node-RED and physical feedback through LEDs and an 8×8 LED matrix.

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📡 System Architecture

[ ESP32 #1 ] ──┐
[ ESP32 #2 ] ──┼──── UDP (Port 2910) ──── [ Raspberry Pi 5 ] ──── HTTP POST ──── [ Node-RED Dashboard ]
[ ESP32 #3 ] ──┘                                │
                                           GPIO LEDs + 8×8 Matrix

Hardware Components

Component	Connected To	Purpose
3× Photoresistor (ADC Pin 34)	ESP32 units	Sense ambient light
3× LED (PWM Pin 23)	ESP32 units	Visual master indicator
1× LED Bar Graph	ESP32 #1	Local light level display
5× LEDs (GPIO 17, 27, 22, 12, 23)	Raspberry Pi	Master device indicator (R/G/B/Y/W)
Push Button (GPIO 24)	Raspberry Pi	Trigger system reset
8×8 LED Matrix MAX7219 (SPI)	Raspberry Pi	Rolling light intensity graph

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📦 Communication Protocol

Binary Packet (ESP ↔ Swarm, every 100ms)

• Length: 14 bytes | Header: 0xF0 | Footer: 0x0F

Packet Type	Description
LIGHT_UPDATE_PACKET	Broadcasts ESP ID, Master State, Light Value (2 bytes)
RESET_SWARM_PACKET	Sent by RPi to force ESP reboot
DEFINE_SERVER_LOGGER_PACKET	Sent by RPi to announce its IP to the swarm

JSON Packet (Master ESP → RPi, every 1000ms)

{ "id": <int>, "light": <int> }

HTTP POST (RPi Python → Node-RED)

Endpoint	Data
/light_data	Real-time photocell traces
/master_duration	Bar chart statistics
/reset	Clears dashboard on button press

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🧠 State Machine (Raspberry Pi)

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🗂️ Repository Structure

code-red-iot/
│
├── raspberry_pi/
│   ├── Code_Red.py              # Main RPi script (UDP listener, LED control, logging)
│
├── esp32/
│   ├── Code_Red.ino             # Main Arduino sketch (shared across all 3 units)
│   └── config.h                 # Per-device config (Device ID, WiFi credentials)
│
├── node_red/
│   └── flows.json               # Node-RED flow export (import directly into Node-RED)
│
├── logs/                        # Auto-generated log files (gitignored sample included)
│   └── sample_log.txt           # Example log output
│
├── docs/
│   ├── schematic.pdf            # Circuit schematic (EasyEDA export)
│   ├── physical_photo.jpg        # Physical circuit photo
│
└── README.md

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🚀 Setup & Installation

Prerequisites

• Raspberry Pi 5 running Raspberry Pi OS
• Arduino IDE with ESP32 board support
• Node-RED installed on RPi (npm install -g --unsafe-perm node-red)

Raspberry Pi Setup

# Install Python dependencies
pip install luma.led-matrix RPi.GPIO requests

# Run the main script
python3 raspberry_pi/main.py

ESP32 Setup

1. Open esp32/esp32_main.ino in Arduino IDE
2. Edit config.h with your WiFi credentials and assign a unique Device ID (1, 2, or 3)
3. Flash to each ESP32 unit

Node-RED Setup

1. Start Node-RED: node-red-start
2. Navigate to http://<rpi-ip>:1880
3. Import node_red/flows.json via the hamburger menu → Import
4. Deploy and open the dashboard at http://<rpi-ip>:1880/ui

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📊 Features

• Swarm Consensus: Devices broadcast light readings every 100ms; the ESP with the highest reading becomes the Master
• Physical Feedback: RPi LEDs change color to indicate which device is currently Master
• LED Matrix Graph: Rolling 30-second history of light intensity displayed on 8×8 matrix
• Live Dashboard: Node-RED displays real-time photocell traces and master duration bar chart
• Persistent Logging: Button press saves a timestamped .txt log and resets the swarm
• Fault Tolerance: Python script continues running even if Node-RED server goes offline

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📁 Log File Format

Each log entry is a comma-separated line: elapsed_time, device_ip, light_value

Log generated at: 2025-12-02_12-27-16
--- Logged information since last Button Press ---
0.111, 192.168.0.169, 1935
3.897, 192.168.0.220, 2117
...

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🛠️ Built With

• luma.led-matrix — MAX7219 driver
• RPi.GPIO — GPIO control
• Node-RED — Visual web dashboard
• Arduino ESP32 — ESP32 firmware

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👤 Author

Arya Sureshbhai Patel