Smart Home IoT Project

Overview

This project is a complete end-to-end Smart Home IoT system that integrates an ESP32 microcontroller with MQTT communication, Node-RED flow processing, Firebase Firestore cloud database, and a Flutter-based mobile application.

The goal is to create a seamless environment where sensor data (temperature, humidity, light) from the ESP32 is sent via MQTT to a cloud broker, routed through Node-RED into Firestore, and then displayed live in a mobile app. The app also allows users to send commands (e.g., turning on/off pins) back to the device through Firestore, creating two-way real-time interaction.

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Project Components

1. ESP32 Firmware

• Purpose: Collect sensor data and send it via MQTT; receive commands to control onboard GPIOs.
• Features:
  • Connects to Wi-Fi (configurable SSID and password).
  • Connects securely to HiveMQ Cloud MQTT broker (mqtts://) using TLS with certificate verification.
  • Publishes randomized sensor values (temperature, humidity, light) to MQTT topics.
  • Subscribes to command topic (home/temperature) and changes WS2812 RGB LED color based on commands:
    • "increase" → Green LED
    • "decrease" → Red LED
    • Others → Blue LED
• Technologies:
  • ESP-IDF framework with FreeRTOS
  • MQTT client from ESP-IDF
  • WS2812 LED control using RMT peripheral
• Customization:
  • Wi-Fi credentials in wifi_config.h
  • MQTT broker URI, username, password in main.c
  • LED GPIO pin and count configurable via macros

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2. MQTT Broker (HiveMQ Cloud)

• Provides a secure, reliable MQTT messaging platform.
• Broker details configured in ESP32 firmware.
• Facilitates MQTT publish-subscribe communication between the ESP32 and Node-RED.

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3. Node-RED Flow

• Acts as a middleware to bridge MQTT and Firestore.
• Subscribes to MQTT sensor data topics (esp/in/temperature, esp/in/humidity, esp/in/light).
• Writes incoming data to corresponding Firestore documents inside the esp32 collection.
• Listens to Firestore commands collection for user commands from the mobile app.
• When a command is detected, Node-RED publishes the command back to MQTT topic (home/temperature), which ESP32 listens to.

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4. Firebase Firestore

• Cloud-hosted NoSQL database storing sensor readings and commands.
• Firestore collections:
  • esp32: Contains documents like temperature, humidity, light with current sensor values.
  • commands: Stores user commands (increase/decrease) with timestamps.
• Enables real-time synchronization between the device and the mobile app.
• Security rules can be customized for read/write access.

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5. Flutter Mobile App

• Cross-platform mobile app built with Flutter and Dart.
• Connects to Firestore to stream sensor data live.
• Displays sensor values dynamically in a list view.
• Provides UI buttons to send increase or decrease commands.
• Commands are written into Firestore commands collection with timestamp.
• User commands are then relayed back to the ESP32 via Node-RED and MQTT.

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How It Works Together

1. ESP32 collects sensor data → publishes via MQTT → HiveMQ broker.
2. Node-RED subscribes to MQTT topics → updates Firestore with sensor data.
3. Flutter app listens to Firestore → displays sensor data live.
4. User presses buttons in Flutter app → writes command to Firestore.
5. Node-RED watches Firestore commands → publishes MQTT command message.
6. ESP32 receives MQTT command → changes LED color or pin state.

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Setup Instructions

ESP32 Firmware

• Configure Wi-Fi and MQTT credentials.
• Compile and flash the firmware using ESP-IDF.
• Ensure HiveMQ Cloud MQTT broker is set up with TLS cert.

Node-RED

• Import the provided Node-RED flow (subscribe MQTT → Firestore, Firestore → publish MQTT).
• Configure MQTT connection to HiveMQ Cloud.
• Configure Firebase Admin credentials for Firestore access.

Firebase Firestore

• Create a Firebase project.
• Enable Firestore in Native mode.
• Set up collections: esp32 (sensor data), commands (control commands).
• Add necessary security rules.

Flutter App

• Add Firebase config files (google-services.json and GoogleService-Info.plist).
• Run flutter pub get to install dependencies.
• Launch the app on an Android/iOS device or emulator.

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Code Highlights

• ESP32 Firmware: Wi-Fi and MQTT setup with event handlers, LED control based on MQTT messages.
• Node-RED: Uses MQTT input/output nodes and Firestore read/write nodes with logic for bidirectional data flow.
• Flutter App: Uses Firestore StreamBuilder for real-time UI updates and Firestore writes for command sending.

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Potential Improvements

• Add secure user authentication on the mobile app.
• Expand supported sensor types and device controls.
• Implement push notifications for sensor alerts.
• Add offline data caching and synchronization.
• Enhance UI/UX with better state management.

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Troubleshooting

• Check Wi-Fi and MQTT connection logs on ESP32 serial console.
• Ensure MQTT broker URI, username, and password are correct.
• Verify Firestore security rules allow read/write from your app and Node-RED.
• Confirm Node-RED credentials for Firebase Admin SDK are valid.
• Use Firebase console to monitor collections and real-time data changes.

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License

This project is licensed under the MIT License. See the LICENSE file for details.

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Acknowledgments

Special thanks to the open source community and the official docs of ESP-IDF, Node-RED, Firebase, HiveMQ, and Flutter for enabling this project.

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If you want help setting up any part or need clarifications, feel free to ask!

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👨‍💻 Author Developed by: [Halime Türkmen] Date: May 2025