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https://github.com/cyberscopetoday/esp8266-htu21d-weather-station

🌡️💧 A low-power weather station project using ESP8266 and HTU21D sensor to measure temperature and humidity and send data to ThingSpeak every 15 minutes.
https://github.com/cyberscopetoday/esp8266-htu21d-weather-station

cpp esp8266 htu21d weather-station

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🌡️💧 A low-power weather station project using ESP8266 and HTU21D sensor to measure temperature and humidity and send data to ThingSpeak every 15 minutes.

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README 

        
# 📡 ESP8266 & HTU21D Weather Station with ThingSpeak Integration



[![CodeFactor](https://www.codefactor.io/repository/github/cyberscopetoday/esp8266-htu21d-weather-station/badge)](https://www.codefactor.io/repository/github/cyberscopetoday/esp8266-htu21d-weather-station)



Measure temperature 🌡️ and humidity 💧 using an ESP8266 microcontroller and an HTU21D sensor, then send the data to ThingSpeak every 15 minutes while conserving power using deep sleep mode 😴.



## 📋 Table of Contents



- [Introduction](#introduction)

- [Components Required](#components-required)

- [Circuit Diagram](#circuit-diagram)

- [Setup Instructions](#setup-instructions)

  - [1. Wiring](#1-wiring)

  - [2. Preparing the ESP8266](#2-preparing-the-esp8266)

  - [3. Setting Up ThingSpeak](#3-setting-up-thingspeak)

  - [4. Programming the ESP8266](#4-programming-the-esp8266)

- [Code Explanation](#code-explanation)

- [Usage](#usage)

- [Troubleshooting](#troubleshooting)

- [License](#license)



## Introduction



This project demonstrates how to build a low-power weather station using the **ESP8266** microcontroller and the **HTU21D** temperature and humidity sensor. The ESP8266 reads data from the sensor and uploads it to **ThingSpeak** every 15 minutes. Between readings, the ESP8266 enters deep sleep mode to conserve power.



## Components Required



- 🧠 **ESP8266** Development Board (e.g., NodeMCU or WeMos D1 Mini)

- 🌡️ **HTU21D** Temperature and Humidity Sensor

- 🔌 Jumper Wires

- 📶 Wi-Fi Network with Internet Access

- 🔋 Power Supply (e.g., USB cable or battery pack)



## Circuit Diagram



🔗 **Connections:**



HTU21D Pin | ESP8266 Pin

---------- | -----------

VCC        | 3.3V

GND        | GND

SDA        | GPIO4 (D2)

SCL        | GPIO5 (D1)



🔌 **Deep Sleep Connection:**



- **GPIO16 (D0)** connected to **RST**



## Setup Instructions



### 1. Wiring



Connect the **HTU21D** sensor to the **ESP8266** as per the connections above.



- Use jumper wires to make the connections.

- Ensure that **GPIO16 (D0)** is connected to **RST** to enable wake-up from deep sleep.



### 2. Preparing the ESP8266



- Install the **Arduino IDE** if you haven't already.

- Add the **ESP8266 board** to the Arduino IDE:

  - Go to **File** > **Preferences**.

  - In **Additional Boards Manager URLs**, add:

    ```

    http://arduino.esp8266.com/stable/package_esp8266com_index.json

    ```

  - Go to **Tools** > **Board** > **Boards Manager**, search for **ESP8266**, and install it.



### 3. Setting Up ThingSpeak



1. Sign up for a free account on [ThingSpeak](https://thingspeak.com/).

2. Create a new **Channel**.

3. Add two fields:

   - **Field 1**: Temperature 🌡️

   - **Field 2**: Humidity 💧

4. Note down your **Channel ID** and **Write API Key**.

   - You'll need these for the code.



### 4. Programming the ESP8266



#### 📦 Libraries Required



Make sure you have the following libraries installed:



- **ESP8266WiFi.h** (comes with ESP8266 core)

- **ThingSpeak.h**

- **Wire.h** (comes with Arduino IDE)

- **SparkFunHTU21D.h**



#### 🔧 Installing Libraries



- **ThingSpeak Library**:

  - Go to **Sketch** > **Include Library** > **Manage Libraries**.

  - Search for **ThingSpeak** and install it.

- **SparkFun HTU21D Library**:

  - Search for **SparkFun HTU21D** and install it.



#### 📝 Code



Replace the placeholders in the code with your Wi-Fi credentials, ThingSpeak Channel ID, and Write API Key.



```cpp

#include 

#include 

#include 

#include 



HTU21D myHTU21D;



const char* ssid = "YOUR_SSID";         // 🔐 Your Wi-Fi SSID

const char* password = "YOUR_PASSWORD"; // 🔑 Your Wi-Fi Password



unsigned long myChannelNumber = YOUR_CHANNEL_NUMBER; // 🆔 Your ThingSpeak Channel ID

const char* myWriteAPIKey = "YOUR_WRITE_API_KEY";    // 📝 Your ThingSpeak Write API Key



WiFiClient client;



void setup() {

  Serial.begin(115200);

  delay(100);



  // 🛠️ Initialize the sensor

  Wire.begin();

  myHTU21D.begin();



  // 📶 Connect to Wi-Fi

  WiFi.begin(ssid, password);

  Serial.println("Connecting to Wi-Fi...");

  while (WiFi.status() != WL_CONNECTED) {

    delay(500);

    Serial.print(".");

  }

  Serial.println("\nConnected to Wi-Fi");



  // 🌐 Initialize ThingSpeak

  ThingSpeak.begin(client);



  // 🌡️💧 Read data from the sensor

  float humidity = myHTU21D.readHumidity();

  float temperature = myHTU21D.readTemperature();



  Serial.print("Temperature: ");

  Serial.print(temperature);

  Serial.println(" *C");



  Serial.print("Humidity: ");

  Serial.print(humidity);

  Serial.println(" %");



  // 📤 Send data to ThingSpeak

  ThingSpeak.setField(1, temperature);

  ThingSpeak.setField(2, humidity);



  int x = ThingSpeak.writeFields(myChannelNumber, myWriteAPIKey);

  if (x == 200) {

    Serial.println("Data successfully sent to ThingSpeak");

  } else {

    Serial.println("Error sending data: " + String(x));

  }



  // 📴 Disconnect Wi-Fi to save power

  WiFi.disconnect(true);

  WiFi.mode(WIFI_OFF);



  // 😴 Enter deep sleep for 15 minutes

  Serial.println("Entering deep sleep for 15 minutes");

  ESP.deepSleep(15 * 60 * 1000000); // Time in microseconds

}



void loop() {

  // The ESP8266 will restart after deep sleep

}

```



#### 🚀 Uploading the Code



1. Connect your ESP8266 to your computer via USB.

2. Select the correct **Board** and **Port** from the **Tools** menu.

3. Click the **Upload** button.



## Code Explanation



- **Libraries Included**:

  - `ESP8266WiFi.h`: Handles Wi-Fi connectivity.

  - `ThingSpeak.h`: Interfaces with ThingSpeak API.

  - `Wire.h`: Enables I2C communication.

  - `SparkFunHTU21D.h`: Communicates with the HTU21D sensor.



- **Global Variables**:

  - Wi-Fi credentials (`ssid`, `password`).

  - ThingSpeak configuration (`myChannelNumber`, `myWriteAPIKey`).

  - `HTU21D` object for sensor interaction.



- **`setup()` Function**:

  - Initializes serial communication for debugging.

  - Initializes the HTU21D sensor.

  - Connects to Wi-Fi.

  - Reads temperature and humidity data.

  - Sends data to ThingSpeak.

  - Disconnects Wi-Fi to save power.

  - Puts the ESP8266 into deep sleep for 15 minutes.



- **`loop()` Function**:

  - Left empty because the ESP8266 will reset after waking up from deep sleep, and the code in `setup()` will run again.



## Usage



- Once uploaded, the ESP8266 will:

  1. Wake up from deep sleep.

  2. Connect to Wi-Fi.

  3. Read sensor data.

  4. Send data to ThingSpeak.

  5. Enter deep sleep for 15 minutes.

  6. Repeat the cycle.



- 📈 View your data on ThingSpeak:

  - Log in to your ThingSpeak account.

  - Navigate to your channel to see real-time updates.



## Troubleshooting



- **Cannot Connect to Wi-Fi**:

  - Double-check your SSID and password.

  - Ensure your Wi-Fi network is 2.4 GHz (ESP8266 does not support 5 GHz).



- **No Data on ThingSpeak**:

  - Verify your **Channel ID** and **Write API Key** are correct.

  - Ensure your ThingSpeak channel is set up properly with the correct fields.



- **ESP8266 Not Waking Up**:

  - Make sure **GPIO16 (D0)** is connected to **RST**.

  - Check your power supply.



- **Error Codes from ThingSpeak**:

  - **-301**: Failed to connect to ThingSpeak.

  - **-302**: Failed to update data.

  - **-401**: Unauthorized (check your API Key).



## License



This project is open-source and available under the MIT License.



---



Enjoy your new low-power weather station! 🌤️ If you have any questions or need further assistance, feel free to ask. Happy coding! 🤖