IoT Monitoring App

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Overview

This Flutter app monitors and configures a connected IoT system (DHT11 sensor) in real time. It connects to a Firebase Realtime Database to display temperature and humidity data, chart their evolution over time, and configure alert thresholds with hysteresis.

Main features

• Current state: real-time temperature and humidity
• Trend chart: sensor data over several time ranges
• Threshold configuration: temperature limits with hysteresis
• Alert history: paginated list of threshold-crossing events
• Offline mode: data persistence through Firebase
• Auto refresh: real-time data updates

Technical architecture

• Frontend: Flutter (Material Design 3)
• Backend: Firebase Realtime Database
• State: Provider
• Charts: fl_chart
• Data model: dedicated models for each data type

Installation

Requirements

• Flutter SDK (^3.6.0)
• Firebase account
• Android Studio / VS Code

Setup

1. Clone the repository

   git clone https://github.com/Yunaluman/rc_mobile_app.git
   cd rc_mobile_app

2. Install dependencies

   flutter pub get

3. Configure Firebase

   Add your firebase_options.dart file at the project root with:

   • apiKey
   • databaseURL
   • the other fields required by FirebaseOptions

4. Run the app

   flutter run

Project structure

lib/
  ├── main.dart              # App entry point
  ├── firebase_options.dart  # Firebase configuration
  ├── models/                # Data models
  │    ├── current_state.dart
  │    ├── sensor_reading.dart
  │    ├── threshold_event.dart
  │    └── time_filter.dart
  ├── services/              # Business logic services
  │    ├── firebase_service.dart
  │    ├── sensor_service.dart
  │    ├── current_state_service.dart
  │    ├── sensor_reading_service.dart
  │    └── threshold_event_service.dart
  ├── utils/                 # Utilities
  │    └── map_converter.dart
  ├── screens/               # Main screens
  │    └── home_screen.dart
  └── widgets/               # Reusable widgets
       ├── current_state_widget.dart
       ├── sensor_readings_chart.dart
       ├── threshold_events_widget.dart
       └── threshold_config_widget.dart

Usage

Main screen

The main screen has several sections:

1. Current state: current temperature and humidity, color-coded against the thresholds
2. Threshold configuration: adjust the temperature alert thresholds
3. Trend chart: data evolution with several time filters
4. Event list: history of threshold crossings

Threshold configuration

Set a target temperature with hysteresis:

• Turn on edit mode with the switch
• Use the slider to set the target temperature
• High (+1 °C) and low (−1 °C) thresholds are computed automatically
• Confirm with the "Save" button

Data models

CurrentState

Current sensor state:

• temperature: current temperature (°C)
• humidity: current humidity (%)
• thresholdLow: low temperature threshold
• thresholdHigh: high temperature threshold
• lastUpdate: last update date
• isOverThreshold: whether the temperature is outside the thresholds

SensorReading

A historical sensor reading:

• temperature: measured temperature (°C)
• humidity: measured humidity (%)
• timestamp: date and time of the measurement

ThresholdEvent

A threshold-crossing event:

• temperature: temperature at the time of the event (°C)
• humidity: humidity at the time of the event (%)
• timestamp: date and time of the event
• eventType: event type (crossing, back to normal)
• thresholdHigh: high threshold at the time of the event
• thresholdLow: low threshold at the time of the event

Services

FirebaseService

Base service for talking to Firebase Realtime Database:

• Connection initialization
• CRUD methods
• Data stream handling
• Connectivity checks
• Safe data type conversion

SensorService

Main service coordinating all sensor services:

• Initializes the specialized services
• Manages app state
• Unified data access interface
• Methods to update thresholds and create events

CurrentStateService

Handles the current sensor state:

• Fetching and updating state
• Temperature threshold configuration
• Threshold-crossing monitoring

SensorReadingService

Handles historical sensor readings:

• Fetching data by time filter
• Processing and filtering readings

ThresholdEventService

Handles threshold-crossing events:

• Creating and fetching events
• Notifying new events

Hysteresis

The system uses hysteresis to avoid rapid flapping between states:

1. The user sets a target temperature (e.g. 23 °C)
2. The system applies a hysteresis margin automatically (±1 °C)
3. The high threshold is set to 24 °C and the low threshold to 22 °C
4. A crossing event is created only when:
   • the temperature rises above the high threshold (> 24 °C)
   • the temperature drops below the low threshold (< 22 °C)
5. The status returns to normal only once the temperature is back within the acceptable range

This avoids false positives and spurious alerts on small temperature fluctuations.

Optimizations and robustness

• Safe conversion of Firebase data types
• Error and connectivity handling
• Data caching for offline mode
• Smart data refresh
• Detailed debug logs

Possible improvements

• User authentication
• Push notifications on threshold crossings
• Support for other sensor types
• Historical data export
• Advanced admin interface

License

Distributed under the MIT license. See the LICENSE file for details.

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Built with ❤️ by Yunaluman THERESE