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Project Documentation

Group Project – Demonstration Website

Overview:

• Gateway collects sensor readings and shares status.
• Nodes wake, send data, briefly listen, then sleep.
• LED colors show overall system state.
• Threshold changes and LED overrides are supported.
• Data published for dashboard viewing.
• Dashboard hosted on Node-RED
• Node-RED handles all the computation for threshold
• See details: System Architecture

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Repository and Libraries

• Repository: https://github.com/Luk446/ArduinoGPProjectDir
• Arduino sketches: Arduino/ESP-Node/ESP-Node.ino, Arduino/ESP-Gateway/ESP-Gateway.ino
• Node-RED flows: Node-RED/flows.json (plus drafts for experiments)

  Libraries Used

• Adafruit_NeoPixel: drive the RGB NeoPixel on nodes.
• DHT sensor library: read temperature/humidity from DHT11.
• ArduinoJson: build/parse MQTT JSON payloads.
• PubSubClient: MQTT client for publishing/subscribing.
• esp_now, WiFi, esp_wifi (ESP32 core): transport and channel configuration.

Design and Architecture

• Hardware: ESP32 Nodes with sensors; ESP32 Gateway connected to host running Node‑RED.
• Network: ESP‑NOW from Nodes to Gateway; optional Wi‑Fi/MQTT beyond Gateway.
• Software: Node publishes alerts/telemetry; Gateway receives and forwards; Node‑RED manages dashboard and alerting.
• More details: Architecture, Arduino Architecture, Node-RED Architecture

Energy Strategies and Encoding

• Duty cycling: Nodes sleep between samples; event‑driven publishing on thresholds.
• Lightweight frames: compact byte/struct payloads for ESP‑NOW; minimal JSON at Gateway only.
• Backoff/retry limits: reduce collisions and radio time; short LED feedback only when debugging.

Deployment and Use

1. Flash firmware: open ESP-Node.ino and ESP-Gateway.ino in Arduino IDE; select ESP32 board; install required libraries; set NODE_ID and Wi‑Fi creds (Gateway if needed); upload.
2. Node‑RED: install and start Node‑RED; import Node-RED/flows.json; configure serial/MQTT nodes to match Gateway; deploy; open dashboard.
3. Run: power Node(s) and Gateway; verify ESP‑NOW peer pairing; trigger thresholds; observe alerts and telemetry.

Reflection

• Deep sleep with 10-second wake cycles achieved 100-200x power reduction (10µA vs 65mA active), while event-driven transmission (send only when temp changes ≥1°C) reduced radio time by 60%
• Node-RED threshold processing offloaded computation from battery nodes to mains-powered host, enabling dynamic threshold updates via MQTT without node reflashing
• Key trade-offs: 10-second sleep interval balanced responsiveness vs battery life, struct packing ensured cross-device compatibility, and RTC memory preserved LED state across sleep cycles at cost of 5ms wake overhead

Future Improvements

• Energy & Reliability: Wake-on-threshold via RTC GPIO interrupts, ACK mechanism for guaranteed LED delivery, battery voltage monitoring with low-power alerts, and watchdog timers for auto-recovery
• Scalability: Auto-discovery via broadcast handshake (eliminate MAC hardcoding), mesh routing for >50m range, hierarchical gateways for 10+ nodes, and InfluxDB integration for historical analysis
• Advanced Features: Web config portal for threshold/WiFi settings, Twilio SMS alerts for critical temps, OTA firmware updates, AES-128 encryption for industrial security, and predictive ML analytics