Sentra

Raspberry Pi-based cold chain and power monitoring system. Tracks fridge temperature and power stability at the edge, stores data locally, serves a live dashboard, and triggers automated alerts via n8n.

Built for unreliable power and low-connectivity environments.

Architecture

Stack

• Hardware: Raspberry Pi 4B, DS18B20, PiJuice UPS HAT
• Data: Python 3, SQLite
• API: Flask, Flask-CORS
• Dashboard: HTML, Chart.js, Lucide Icons
• Automation: n8n (via Docker), Telegram API
• Future: RS485/Modbus (Waveshare adapter), Cloudflare Tunnel

Structure

sentra/
├── scripts/
│   ├── monitor.py          # Sensor collection + anomaly detection
│   └── api_server.py       # REST API
├── dashboard/
│   └── index.html          # Monitoring dashboard
├── docker/
│   ├── docker-compose.yml  # n8n container config
│   └── n8n_workflow.json   # Alert workflow
├── docs/
│   └── WIRING.md           # Hardware connection guide
├── data/                   # SQLite DB (runtime, gitignored)
├── logs/                   # App logs (runtime, gitignored)
└── netlify.toml            # Deploy config

Setup

# Clone and create venv
git clone https://github.com/monfortbrian/sentra-cold-chain-monitoring.git
cd sentra && python3 -m venv venv && source venv/bin/activate
pip install flask flask-cors requests schedule

# Enable 1-Wire
sudo raspi-config  # Interface Options → 1-Wire → Enable
sudo reboot

# Install services
sudo cp docs/sentra-*.service /etc/systemd/system/
sudo systemctl daemon-reload
sudo systemctl enable --now sentra-monitor sentra-api

# Start n8n
cd docker && docker compose up -d

Dashboard: http://<PI_IP>:5000 n8n: http://<PI_IP>:5678

API

Method	Endpoint	Returns
GET	/api/health	{ status, readings }
GET	/api/status	Current temp, battery, power, incident count
GET	/api/temperature?hours=24	Temp readings + min/max/avg stats
GET	/api/battery?hours=24	Battery % history
GET	/api/incidents?limit=50	Incident log
GET	/api/summary?days=7	Compliance report data
POST	/api/incidents/<id>/acknowledge	Mark incident acknowledged

Hardware

See docs/WIRING.md for DS18B20 and PiJuice connection guide.

License

MIT

Contact

monfortnkurunziza0@gmail.com