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Last updated on Sep 10, 2024
Last updated on Mar 12, 2024
Ever wished you could monitor the temperature and humidity in your home, greenhouse, or any environment you care about, right from your smartphone? This blog will guide you through building your own temperature and humidity monitoring system using readily available components and Flutter for the mobile application.
We'll explore the hardware setup, delve into the world of sensor communication, and finally, build a user-friendly app with Flutter to visualize the data.
Maintaining ideal temperature and humidity levels is crucial for various environments. In homes, it can affect comfort levels, and air quality, and even prevent mold growth. Greenhouses thrive with specific temperature and humidity ranges for optimal plant growth.
This DIY project allows you to build a system that constantly monitors these critical environmental factors and provides real-time data on your smartphone.
Flutter, a modern mobile app development framework known for its cross-platform capabilities and rich UI elements, will be used to create the user interface for our monitoring system. With Flutter, you can build a single codebase that runs seamlessly on both Android and iOS devices.
Here's a list of the components you'll need to build your system:
These digital sensors output temperature and humidity readings. DHT sensors are popular choices due to their affordability, but they require a dedicated data pin on the microcontroller. BME280 offers additional features like barometric pressure sensing and communicates via I2C protocol, freeing up microcontroller pins for other functionalities.
This acts as the brain of the system, reading data from the sensor, formatting it, and transmitting it to the phone app via Bluetooth or WiFi. Arduino Uno is a popular beginner-friendly option, while ESP32 offers additional features like built-in WiFi and Bluetooth.
These thin wires connect the various components on the breadboard or directly to the microcontroller. Choose different colors for easier identification.
This provides a convenient platform for prototyping the circuit before finalizing connections on the microcontroller board.
Power the microcontroller board using a USB cable connected to your computer or a mobile power bank for portability.
Here's how to set up the hardware for your temperature and humidity monitoring system:
Both DHT and BME sensors have their pros and cons. DHT sensors (DHT11/DHT22) are inexpensive and easy to use, but they require a dedicated data pin on the microcontroller and have a slightly lower accuracy compared to BME280. BME280 offers higher accuracy, and additional functionalities like barometric pressure sensing, and communicates via I2C protocol, freeing up microcontroller pins. We'll provide connection diagrams for both sensor options.
If using a breadboard, connect the following pins:
If connecting directly to the microcontroller board without a breadboard, refer to the specific pin layout for your board and connect accordingly.
The microcontroller code acts as the conductor of your temperature and humidity monitoring system. It orchestrates communication between the sensor and your phone app, ensuring data flows seamlessly. Here's a closer look at its functionalities:
For Arduino boards, the primary programming language used is Arduino C++. It's a simplified version of C++ designed for microcontroller development, making it easier to learn and use compared to standard C++.
a) Sensor Initialization:
b) Reading Temperature and Humidity Data:
c) Formatting Data for Transmission:
{"temperature": 25.0, "humidity": 60.0}
, where "temperature" and "humidity" are labels for the corresponding values.d) Communication and Data Transmission (Choosing Bluetooth or WiFi): i) Bluetooth Communication:
ii) WiFi Communication:
Remember, the specific code implementation will vary depending on the chosen sensor, communication method, and desired functionalities. However, this breakdown provides a high-level understanding of the core functionalities handled by the microcontroller code in your temperature and humidity monitoring system.
Now that we have the hardware and communication methods set up, let's build the Flutter app to visualize the temperature and humidity data from the sensor.
Make sure you have Flutter installed on your development machine (refer to the official documentation for installation instructions: https://docs.flutter.dev/get-started/install ).
Create a new Flutter project using the command line tool: flutter create my_sensor_app.
Open the project directory in your preferred code editor (e.g., Visual Studio Code).
To connect with the chosen communication method (Bluetooth, WiFi, or cloud platform) in your Flutter app, you'll need to add relevant packages to the pubspec.yaml file. Here are some common options:
a. Bluetooth: Use the flutter_blue package (https://pub.dev/packages/flutter_blue_pro ) to discover, connect, and communicate with Bluetooth devices.
b. WiFi: For simple HTTP communication, the built-in http package in Flutter can be used. For more advanced features like web sockets, consider packages like web_socket_channel (https://pub.dev/packages/web_socket_client ).
c. Cloud Platforms: Cloud platforms like Firebase and ThingSpeak offer their own Flutter libraries or SDKs. Refer to their documentation for specific package names and integration instructions.
Use the Material package included with Flutter to design a user-friendly interface for your app. Consider including elements like:
Here's a breakdown of communication logic based on different scenarios:
a. Bluetooth Communication:
1import 'package:flutter/material.dart'; 2import 'package:flutter_blue/flutter_blue.dart'; 3 4void main() { 5 runApp(MyApp()); 6} 7 8class MyApp extends StatelessWidget { 9 10 Widget build(BuildContext context) { 11 return MaterialApp( 12 home: MyHomePage(), 13 ); 14 } 15} 16 17class MyHomePage extends StatefulWidget { 18 19 _MyHomePageState createState() => _MyHomePageState(); 20} 21 22class _MyHomePageState extends State<MyHomePage> { 23 BluetoothDevice? connectedDevice; 24 double temperature = 0.0; 25 double humidity = 0.0; 26 27 28 void initState() { 29 super.initState(); 30 FlutterBlue.instance.scanResults.listen((results) { 31 // Discover Bluetooth devices and search for your sensor device 32 for (ScanResult result in results) { 33 if (result.device.name == "Your Sensor Name") { // Replace with actual device name 34 connectedDevice = result.device; 35 connectDevice(); 36 break; 37 } 38 } 39 }); 40 } 41 42 void connectDevice() async { 43 try { 44 await connectedDevice!.connect(); 45 listenForData(); 46 } catch (e) { 47 // Handle connection errors 48 print("Connection error: $e"); 49 } 50 } 51 52 void listenForData() async { 53 await connectedDevice!.services.then((services) { 54 for (BluetoothService service in services) { 55 // Find the characteristic used for data transmission 56 service.characteristics.then((characteristics) { 57 for (BluetoothCharacteristic characteristic in characteristics) { 58 if (characteristic.uuid.toString() == "your_characteristic_uuid") { // Replace with actual characteristic UUID 59 characteristic.value.listen((data) { 60 // Parse received data (e.g., JSON format) and update UI 61 String dataString = String.fromCharCodes(data); 62 var jsonData = jsonDecode(dataString); 63 temperature = jsonData["temperature"]; 64 humidity = jsonData["humidity"]; 65 setState(() {}); // Update UI with new readings 66 }); 67 characteristic.setNotifyValue(true); // Enable notifications for data updates 68 } 69 } 70 }); 71 } 72 }); 73 } 74 75 76 Widget build(BuildContext context) { 77 return Scaffold( 78 appBar: AppBar( 79 title: Text("Temperature & Humidity Monitor"), 80 ), 81 body: Center( 82 child: Column( 83 mainAxisAlignment: MainAxisAlignment.center, 84 children: [ 85 Text( 86 "Temperature: $temperature °C", 87 style: TextStyle(fontSize: 24), 88 ), 89 Text( 90 "Humidity: $humidity %", 91 style: TextStyle(fontSize: 24), 92 ), 93 ], 94 ), 95 ), 96 ); 97 } 98}
Explanation: This example demonstrates fetching data from a sensor connected to your WiFi network using a simple HTTP GET request.
Remember to replace "http://your_sensor_ip/data" with the actual URL endpoint where your sensor exposes the data.
b. Cloud Communication: The implementation for cloud communication will vary based on the chosen platform (Firebase, ThingSpeak, etc.). Refer to their respective Flutter libraries and documentation for specific instructions. Generally, you'll use platform-specific methods to connect to the cloud platform, retrieve sensor data stored there, and update the UI in your app.
Thoroughly test the app on your device by connecting to the sensor using the chosen communication method. Verify that data is received and displayed correctly.
For deployment, consider sideloading the app on your Android device for personal use. Refer to Flutter documentation for app deployment options on different platforms (https://docs.flutter.dev/deployment ).
By following this comprehensive guide, you've built a DIY temperature and humidity monitoring system using readily available components and Flutter. You now have a mobile app that provides real-time data visualization and allows you to monitor your environment remotely.
This project serves as a foundation for further exploration. You can customize it to suit your specific needs, add new functionalities like controlling connected devices based on sensor readings (e.g., smart home applications), or explore integrating with advanced analytics platforms. With a little creativity and perseverance, you can turn this DIY project into a powerful tool for monitoring and managing your environment.
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