ESP32 Tutorial 43/55 - IoT Internet Weather Station | SunFounder's ESP32 IoT Learning kit

本课是……的一部分: 基于 SunFounder ESP32 IoT 学习套件的 ESP32 Arduino 课程（55 个教程/视频）

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ESP32 Tutorial 43/55 - IoT Internet Weather Station | SunFounder's ESP32 IoT Learning kit

In this tutorial, we will build an Internet-connected weather station using the ESP32 and its camera extension board from SunFounder. This project enables the ESP32 to retrieve real-time weather data, including temperature and humidity, and display it on an LCD screen. This application not only showcases the capabilities of the ESP32 but also demonstrates how to fetch and parse data from an external API.

As we progress through the tutorial, we will wire the components, configure the code, and ensure everything works seamlessly together. The end result will be a fully functional weather station that updates its readings every 10 seconds, providing a clear and concise display of current weather conditions (in video at 00:30).

Hardware Explained

The main components used in this project include the ESP32 microcontroller, an LCD display, and the necessary wiring. The ESP32 is equipped with built-in Wi-Fi and Bluetooth, allowing it to connect to the Internet and retrieve data. The LCD display will show the current weather information, including temperature and humidity.

The LCD we are using is a 16x2 character display, which means it can show two lines of 16 characters each. This will be sufficient for our weather information output. The ESP32 will communicate with the LCD via I2C, which simplifies the wiring by using only two data lines.

Datasheet Details

Manufacturer	Espressif
Part number	ESP32-WROOM-32
Logic/IO voltage	3.3 V
Supply voltage	3.0–3.6 V
Output current (per channel)	12 mA max
Peak current (per channel)	40 mA
PWM frequency guidance	1 kHz
Input logic thresholds	0.3 V (low), 0.7 V (high)
Voltage drop / R_DS(on) / saturation	0.5 V
Thermal limits	-40 to 85 °C
Package	QFN48
Notes / variants	Includes multiple variants for different applications

Ensure the ESP32 is powered with a stable 3.3 V supply.
Use a common ground for all components to avoid communication issues.
Check the I2C address of the LCD using an I2C scanner.
Monitor the Wi-Fi connection status to avoid disconnections during data fetching.
Handle JSON parsing errors for robustness in data retrieval.

Wiring Instructions

To wire the components, start by connecting the LCD to the ESP32. The LCD will use the I2C interface, so connect the SDA pin of the LCD to GPIO21 on the ESP32 and the SCL pin to GPIO22. Make sure to connect the power and ground pins of the LCD to the 5V and GND pins on the ESP32, respectively.

Next, ensure that the ESP32 is powered correctly using the included lithium battery or a USB connection. The battery provides portability, while the USB connection is useful for programming and debugging. Finally, check all connections are secure to avoid any loose wiring issues that could disrupt functionality.

Code Examples & Walkthrough

In the setup phase of our program, we initialize the serial communication and connect to the Wi-Fi network using the provided SSID and password. The following code snippet handles the Wi-Fi connection:

WiFi.begin(ssid, password);
while(WiFi.status() != WL_CONNECTED) {
  delay(500);
  Serial.print(".");
}
Serial.println("Connected to WiFi network with IP Address: ");
Serial.println(WiFi.localIP());

This code ensures that the ESP32 connects to the specified Wi-Fi network before proceeding with any data fetching. If the connection fails, it will continuously attempt to reconnect.

Next, we need to send an HTTP GET request to retrieve weather data. This is accomplished using the following code snippet:

String serverPath = "http://api.openweathermap.org/data/2.5/weather?q=" + city + "," + countryCode + "&units=metric" + "&APPID=" + openWeatherMapApiKey;
jsonBuffer = httpGETRequest(serverPath.c_str());

Here, we construct the URL for the API request, which includes the city, country code, and our API key. The httpGETRequest function is then called to fetch the weather data.

Finally, we parse the JSON response and display the relevant data on the LCD:

lcd.clear(); 
lcd.setCursor(0, 0); 
lcd.print(time);
lcd.print(" ");        
lcd.print(myObject["weather"][0]["main"]);             
lcd.setCursor(0, 1);
lcd.print("T:");    
lcd.print(myObject["main"]["temp"]); 
lcd.print("\xDF");  // "°" char
lcd.print("C ");    
lcd.print("H:");    
lcd.print(myObject["main"]["humidity"]);  
lcd.print("%");

This code snippet updates the LCD display with the current time, weather condition, temperature, and humidity. It clears the previous display and sets the cursor to the appropriate positions for each line.

Demonstration / What to Expect

Upon successful wiring and programming, your weather station will connect to the Wi-Fi and start fetching weather data every 10 seconds. You'll see the current temperature, humidity, and weather conditions displayed on the LCD screen. If the ESP32 fails to connect to Wi-Fi, it will print an error message to the serial monitor.

Be mindful of the API call limits to avoid being blocked from the OpenWeatherMap service. If you encounter any issues with data retrieval, check your API key and ensure your city and country code are correctly specified (in video at 15:45).