HeatSync

Real-Time IoT Environmental Monitoring System

Abstract

HeatSync is a full-stack Internet of Things (IoT) solution designed for the real-time monitoring and analysis of environmental conditions (temperature and humidity) within complex building infrastructures. The system employs a distributed architecture comprising low-power edge devices, a centralized message broker, and a reactive web dashboard to ensure scalable and reliable data acquisition.

System Architecture

The HeatSync system operates on a publish-subscribe model to decouple data acquisition from data processing and visualization.

graph TD
    subgraph "Edge Layer"
        ESP32[ESP32 Node] -- "Reads Data" --> Sensor[DHT11 Sensor]
        ESP32 -- "MQTT (JSON)" --> Broker[MQTT Broker]
    end

    subgraph "Backend Layer"
        Broker -- "Subscribes" --> NestJS[NestJS Server]
        NestJS -- "Persists" --> DB[(PostgreSQL)]
        NestJS -- "Socket.IO" --> Client[Web Client]
    end

    subgraph "Frontend Layer"
        Client -- "HTTP/REST" --> NestJS
        User[User] -- "Interacts" --> Client
    end

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Data Flow

1. Acquisition: The ESP32 microcontroller polls the DHT11 sensor at a configurable interval.
2. Transmission: Telemetry data (Device ID, Temperature, Humidity, Timestamp) is serialized into JSON and published to the heatsync/telemetry MQTT topic.
3. Ingestion: The NestJS backend subscribes to the telemetry topic. Upon receiving a message, it validates the payload and checks for alert thresholds.
4. Persistence: Validated data is stored in a PostgreSQL database using Drizzle ORM for historical analysis.
5. Broadcast: The backend pushes the new data point to connected frontend clients via WebSocket (Socket.IO) for real-time visualization.

Hardware Layer

The edge component is built on the ESP32 microcontroller, chosen for its dual-core architecture and integrated Wi-Fi/Bluetooth capabilities.

• Microcontroller: ESP32-WROOM-32
• Sensor: DHT11 (Temperature & Humidity)
• Protocol: MQTT over TCP/IP
• Firmware Logic:
  • Network provisioning and reconnection strategies.
  • NTP time synchronization for accurate timestamping.
  • Deep sleep capabilities (planned) for power optimization.

Software Layer

Backend (NestJS)

The backend is a modular application built with NestJS, providing a robust architecture for handling IoT streams.

• MQTT Service: Manages connection to the broker and handles incoming telemetry.
• WebSocket Gateway: Manages real-time bidirectional communication with the frontend.
• Alert System: Evaluates incoming data against user-defined thresholds to trigger notifications.
• Database: PostgreSQL managed via Drizzle ORM. The schema supports a hierarchical location model: $$Building \rightarrow Sector \rightarrow Floor \rightarrow Room \rightarrow Device$$

Frontend (Next.js)

The user interface is a Next.js application focusing on data visualization and device management.

• Real-Time Dashboard: Updates instantly as data arrives via WebSockets.
• Hierarchical Filtering: Allows users to drill down data from an entire building to a specific room.
• Tech Stack: React, Tailwind CSS, shadcn/ui.

Key Features

• Real-time dashboard: Live updates with Socket.IO.
• Hierarchical device filtering: $Building \rightarrow Sector \rightarrow Floor \rightarrow Room \rightarrow Device$
• Alert system: Threshold violations for temperature/humidity.
• Authentication: Secure access via Supabase Auth.
• Data export: Export capabilities for selected date ranges.

Tech Stack

Category	Technology
Frontend	Next.js, React.js, shadcn/ui
Backend	NestJS, Socket.io, Drizzle ORM
Device / Firmware	ESP32 with PlatformIO
Database	PostgreSQL
MQTT	Mosquitto MQTT
Email API	Resend
Authentication	Supabase Auth
Hosting	Render, Vercel, Supabase, HiveMQ

Research & Future Work

This project aims to address several critical challenges in deploying IoT systems in real-world scenarios:

1. Extreme Environment Operation:

   • Validating ESP32 stability and sensor accuracy in sub-zero temperatures (e.g., industrial freezers).
   • Analyzing battery performance and discharge rates in cold environments.

2. Network Reliability in Restricted Environments:

   • Overcoming connectivity issues in corporate networks with strict firewalls and proxy configurations.
   • Evaluating fallback communication protocols (LoRaWAN, Cellular) for redundancy.

3. Data Integrity & Redundancy:

   • Implementing local buffering on the ESP32 to prevent data loss during network outages.
   • Synchronization algorithms to upload buffered data upon reconnection.

4. Regulatory Compliance:

   • Ensuring hardware compliance with telecommunications standards (e.g., ANATEL).
   • Adhering to data storage and privacy regulations for research data.