Pi-Connect 2.0 🔌

Production-grade, zero-interference WiFi configuration system for headless Raspberry Pi via Bluetooth Low Energy

🎯 Overview

Pi-Connect 2.0 is a sophisticated IoT solution that enables WiFi configuration on headless Raspberry Pi devices through a secure Bluetooth Low Energy (BLE) interface. Designed with a "set-and-forget" philosophy, it operates as an intelligent system service that minimizes resource consumption while maximizing reliability.

The Problem It Solves

Configuring WiFi on a Raspberry Pi without a display, keyboard, or Ethernet connection is notoriously difficult. Traditional solutions require:

Pre-configuration of WiFi credentials before deployment
Physical access to edit files on the SD card
Temporary Ethernet connections
Complex command-line operations

The Pi-Connect 2.0 Solution

✅ Configure WiFi from any smartphone or laptop with Bluetooth
✅ No display, keyboard, or Ethernet required
✅ Secure HMAC-SHA256 authentication
✅ Automatic power management (BLE turns off when connected)
✅ Hardware rescue button for field recovery
✅ Zero interference with primary Pi applications

✨ Key Features

🔐 Enterprise-Grade Security

HMAC-SHA256 authentication with nonce-based challenge-response
Replay protection prevents credential theft
Configurable shared secrets via environment variables
No plaintext transmission of sensitive data

🤖 Intelligent State Machine

BOOT: Auto-detects internet connectivity
IDLE: Sleeps when WiFi is connected (60sec check intervals)
ADVERTISING: Activates BLE only when needed
CONNECTING: Pauses watchdog during credential processing

⚡ Zero-Interference Design

CPU usage: <1% when idle
Memory: <100MB max
Aggressive sleep intervals
Low process priority (Nice: 10)
No conflicts with robotics, AI, or IoT workloads

🛡️ Hardware Rescue Button

Force configuration mode with 5-second long press
Uses safe GPIO 27 (avoids HAT conflicts)
Perfect for field deployments
Optional LED status indicator

📱 Modern Web Interface

Single-file HTML deployment (works on Vercel, GitHub Pages, or locally)
Web Bluetooth API - no app installation required
Dark mode UI with real-time status updates
Cross-platform: Works on Chrome (desktop/Android), Edge, Opera

🔄 Robust Network Management

Uses NetworkManager (nmcli) for reliable connections
Internet connectivity verification (ping 8.8.8.8)
Gateway detection for local networks
Automatic retry logic
Clean connection state management

🏗️ Architecture

┌─────────────────────────────────────────────────────────────┐
│                     Pi-Connect 2.0 System                   │
├─────────────────────────────────────────────────────────────┤
│                                                             │
│  ┌──────────────┐      ┌───────────────┐     ┌──────────┐ │
│  │ State Machine│◄─────┤   Watchdog    │────►│ Network  │ │
│  │   (Reactive) │      │   (Thread)    │     │ Manager  │ │
│  └──────────────┘      └───────────────┘     └──────────┘ │
│         │                                           │      │
│         ▼                                           ▼      │
│  ┌──────────────┐      ┌───────────────┐     ┌──────────┐ │
│  │ BLE GATT     │◄────►│   Security    │     │  GPIO    │ │
│  │ Server       │      │   Manager     │     │  Button  │ │
│  │ (BlueZ/D-Bus)│      │   (HMAC)      │     │ (Thread) │ │
│  └──────────────┘      └───────────────┘     └──────────┘ │
│         │                      ▲                           │
│         │                      │                           │
└─────────┼──────────────────────┼───────────────────────────┘
          │                      │
          │ BLE Connection       │ Credentials
          ▼                      │
    ┌──────────────────────────────────────┐
    │   Web Client (Vite App)              │
    │   - Web Bluetooth API                │
    │   - HMAC-SHA256 Calculation          │
    │   - Real-time Status Updates         │
    └──────────────────────────────────────┘

📦 What's Included

1. Backend Service (`pi_connect.py`)

650+ lines of production-ready Python
Complete state machine implementation
BlueZ GATT server via D-Bus
NetworkManager integration
GPIO button handler with debouncing
Rotating file logger (1MB max, 5 backups)
Comprehensive error handling

2. Web Client (Vite + ES Modules)

Modern build tooling with Vite
Web Bluetooth API integration
Crypto-JS for HMAC calculation
Secure environment variables (.env)
Modern dark mode interface
Real-time BLE notifications
Optimized production builds

3. System Service (`pi-connect.service`)

Systemd unit file
Auto-start on boot
Resource limits (CPU quota, memory cap)
Security hardening options
Environment variable support

4. Documentation

HARDWARE_GUIDE.md: Complete GPIO wiring instructions
INSTALLATION.md: Step-by-step setup guide
README.md: Project overview and architecture
QUICK_REFERENCE.md: Command cheat sheet

5. Web Client Files

src/main.js: Application logic (ES modules)
index.html: Main HTML template
package.json: Dependencies and build scripts
vite.config.js: Vite configuration
.env.example: Environment variable template

🚀 Quick Start

1. Install on Raspberry Pi

# Clone or download the project
cd /tmp

# Run installation
sudo apt update
sudo apt install -y python3 python3-pip python3-dbus python3-gi \
    bluetooth bluez network-manager gpiozero

pip3 install pydbus --break-system-packages

# Deploy files
sudo mkdir -p /opt/pi-connect
sudo cp pi_connect.py /opt/pi-connect/
sudo cp pi-connect.service /etc/systemd/system/

# Generate and set shared secret
SECRET=$(openssl rand -base64 32)
echo "Your secret: $SECRET"
# Update pi-connect.service with this secret

# Start service
sudo systemctl daemon-reload
sudo systemctl enable pi-connect
sudo systemctl start pi-connect

2. Deploy Web Interface

# Install dependencies
npm install

# Create .env file and set your shared secret
cp .env.example .env
# Edit .env: VITE_SHARED_SECRET=your_secret_here

# Development (with hot reload)
npm run dev

# Production build
npm run build

# Deploy to Vercel: Push to GitHub, import to vercel.com
# Set VITE_SHARED_SECRET in Vercel environment variables

3. Connect and Configure

Open web interface on phone/laptop
Enable Bluetooth
Click "Connect to Pi"
Enter WiFi credentials
Click "Configure WiFi"
Done! 🎉

Detailed instructions: See INSTALLATION.md

🔧 Hardware Requirements

Minimum Requirements

Raspberry Pi 3B+ or newer (built-in Bluetooth)
Raspberry Pi OS Bookworm or Bullseye
8GB+ SD card
Power supply (5V 2.5A minimum)

Optional Components

Momentary push button (for rescue mode)
LED indicator (for visual feedback)
10kΩ resistor (if not using internal pull-up)

Wiring Guide: See HARDWARE_GUIDE.md

🔒 Security Model

Authentication Flow

Client                          Pi
  │                              │
  │──── Connect to BLE ─────────>│
  │                              │
  │<──── Read Nonce ─────────────│ (32-byte random)
  │                              │
  │  Calculate HMAC:             │
  │  H = HMAC-SHA256(            │
  │    secret,                   │
  │    nonce + ssid + password   │
  │  )                           │
  │                              │
  │──── Write HMAC ─────────────>│
  │                              │ Verify HMAC
  │                              │ ✓ Valid? Continue
  │                              │ ✗ Invalid? Disconnect
  │──── Write SSID ─────────────>│
  │──── Write Password ─────────>│
  │                              │
  │<──── Status Updates ─────────│ (via BLE Notify)

Security Features

✅ Nonce expires after 60 seconds
✅ One-time use (replay protection)
✅ Constant-time HMAC comparison
✅ No credential logging
✅ Secure credential clearing after use
✅ TLS for web interface (if hosted on Vercel)

⚠️ Important Security Notes

Change the default shared secret immediately
Use a cryptographically random secret (32+ characters)
Keep secret confidential - never commit to public repos
Same secret must be configured on both Pi and web client
Consider physical security of GPIO button access

📊 Performance Characteristics

Resource Usage (Measured on Pi 3B+)

State	CPU Usage	Memory	BLE Status
IDLE (WiFi connected)	<0.5%	~30MB	OFF
ADVERTISING (No WiFi)	~1%	~35MB	ON
CONNECTING	~2%	~40MB	ON

Timing

Boot detection: ~2 seconds
State transition: ~1-2 seconds
WiFi connection: 10-30 seconds (network dependent)
IDLE check interval: 60 seconds
Advertising check interval: 10 seconds

Why Zero-Interference?

Uses time.sleep() aggressively
Low process priority (Nice: 10)
SystemD CPU quota: 10%
Memory limit: 100MB
No polling loops in critical paths
BLE radio OFF when not needed

🧪 Testing

Unit Tests

# Test network connectivity
python3 -c "from pi_connect import NetworkManager; print(NetworkManager.is_connected())"

# Test GPIO button
python3 -c "from gpiozero import Button; b = Button(27); print('Press button...'); b.wait_for_press(); print('Detected!')"

Integration Tests

# Monitor service logs
sudo journalctl -u pi-connect -f

# Test state transitions
# 1. Disable WiFi → Should enter ADVERTISING
# 2. Enable WiFi → Should return to IDLE
# 3. Press button 5s → Should force ADVERTISING

End-to-End Test

Deploy fresh Raspberry Pi OS
Run installation script
Boot without WiFi
Connect via web interface
Configure WiFi
Verify automatic IDLE transition
Test button rescue mode

🐛 Troubleshooting

Service won't start

# Check detailed logs
sudo journalctl -u pi-connect -n 100 --no-pager

# Common fixes:
sudo systemctl restart bluetooth
sudo rfkill unblock bluetooth
pip3 install pydbus --break-system-packages

Can't see Pi in Bluetooth scan

# Verify advertising
sudo hcitool lescan

# Check state
sudo journalctl -u pi-connect | grep "State transition"

Web Bluetooth not working

✅ Use Chrome, Edge, or Opera (NOT Safari/Firefox)
✅ Enable Bluetooth on device
✅ Use HTTPS (required by Web Bluetooth API)
✅ Grant Bluetooth permissions when prompted

Authentication fails

Check shared secret matches in both:
- /etc/systemd/system/pi-connect.service
- index.html CONFIG.SHARED_SECRET
Regenerate secret and update both sides

Full troubleshooting guide: See INSTALLATION.md

🛣️ Roadmap

Version 2.1 (Planned)

Multiple WiFi network profiles
Network priority/fallback
WPA Enterprise support
Mobile app (React Native)

Version 2.2 (Future)

Web dashboard for Pi status
Remote SSH tunnel setup
Automatic backup credentials
OTA (Over-The-Air) updates

Contributions Welcome!

See CONTRIBUTING.md for guidelines (submit PRs, report issues)

📄 License

MIT License - See LICENSE file for details

🙏 Acknowledgments

BlueZ Project - Linux Bluetooth stack
NetworkManager - WiFi connection management
gpiozero - GPIO control library
Web Bluetooth Community - Browser API standardization
Raspberry Pi Foundation - Amazing hardware platform

📞 Support

Issues: GitHub Issues
Documentation: See INSTALLATION.md and HARDWARE_GUIDE.md
Community: Raspberry Pi Forums

🎓 Use Cases

Perfect for:

🤖 Robotics projects
🏠 Home automation (Home Assistant)
📡 IoT sensor networks
🎓 Educational projects
🔬 Research equipment
📹 Headless camera systems
🎵 Audio streaming devices

Made with ❤️ for the Raspberry Pi Community

If this project helped you, consider starring it on GitHub! ⭐

Name		Name	Last commit message	Last commit date
Latest commit History 9 Commits
src		src
.env.example		.env.example
.gitignore		.gitignore
HARDWARE_GUIDE.md		HARDWARE_GUIDE.md
INSTALLATION.md		INSTALLATION.md
QUICK_REFERENCE.md		QUICK_REFERENCE.md
README.md		README.md
index.html		index.html
package-lock.json		package-lock.json
package.json		package.json
pi-connect.service		pi-connect.service
pi_connect.py		pi_connect.py
vercel.json		vercel.json
vite.config.js		vite.config.js

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Pi-Connect 2.0 🔌

🎯 Overview

The Problem It Solves

The Pi-Connect 2.0 Solution

✨ Key Features

🔐 Enterprise-Grade Security

🤖 Intelligent State Machine

⚡ Zero-Interference Design

🛡️ Hardware Rescue Button

📱 Modern Web Interface

🔄 Robust Network Management

🏗️ Architecture

📦 What's Included

1. Backend Service (pi_connect.py)

2. Web Client (Vite + ES Modules)

3. System Service (pi-connect.service)

4. Documentation

5. Web Client Files

🚀 Quick Start

1. Install on Raspberry Pi

2. Deploy Web Interface

3. Connect and Configure

🔧 Hardware Requirements

Minimum Requirements

Optional Components

🔒 Security Model

Authentication Flow

Security Features

⚠️ Important Security Notes

📊 Performance Characteristics

Resource Usage (Measured on Pi 3B+)

Timing

Why Zero-Interference?

🧪 Testing

Unit Tests

Integration Tests

End-to-End Test

🐛 Troubleshooting

Service won't start

Can't see Pi in Bluetooth scan

Web Bluetooth not working

Authentication fails

🛣️ Roadmap

Version 2.1 (Planned)

Version 2.2 (Future)

Contributions Welcome!

📄 License

🙏 Acknowledgments

📞 Support

🎓 Use Cases

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1. Backend Service (`pi_connect.py`)

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