ESP8266 Weather Station with OLED Display

A weather station based on ESP8266 with SSD1306 OLED display, DHT22 sensor, and OpenWeatherMap API integration.

Features

• SSD1306 OLED Display (128x64) connected via I2C (SDA=GPIO12, SCL=GPIO14)
• DHT22 Sensor (GPIO4) for local temperature and humidity readings
• OpenWeatherMap Integration for weather forecast (current + 2 future periods)
• NTP Time Synchronization for accurate time display
• WiFi Signal Indicator with simple bar-style icon
• Weather Icons (sun, clouds, rain, thunderstorm, snow, mist)
• Day of Week Display for each forecast period (Sun, Mon, Tue, Wed, Thu, Fri, Sat)
• KConfig-based Configuration for all critical parameters

Hardware Requirements

• ESP8266 (NodeMCU, Wemos D1 Mini, etc.)
• SSD1306 OLED Display 128x64 (I2C)
• DHT22 Sensor Module (AM2302) with built-in pull-up resistor

Wiring

Component	GPIO	Physical Pin
SSD1306 SDA	GPIO12 (D6)	-
SSD1306 SCL	GPIO14 (D5)	-
DHT22 Data	GPIO4 (D2)	-
DHT22 VCC	3.3V	-
DHT22 GND	GND	-

Environment Setup

Prerequisites

1. ESP8266_RTOS_SDK installed
2. ESP8266 toolchain configured

Set environment variables

export IDF_PATH=/path/to/ESP8266_RTOS_SDK
export PATH="$IDF_PATH/tools:$PATH"

Build and Flash

1. Configure the project

cd /path/to/esp8266_weather_oled
idf.py menuconfig

Configure the following parameters under Weather Station Configuration:

WiFi Configuration

• WiFi SSID: Your WiFi network name
• WiFi Password: Network password
• Maximum retry attempts: Connection retry attempts (default: 5)

OpenWeatherMap API Configuration

• OpenWeatherMap API Key: Your API key (get it at https://openweathermap.org/api)
• City name: City name (e.g., "New York", "London", "Tokyo")
• Country code: Country code (e.g., "US", "GB", "JP")
• Weather update interval: Update interval in minutes (default: 30)

Time Configuration

• NTP Server: NTP server address (default: "pool.ntp.org")
• Timezone: Timezone string (e.g., "UTC-5", "UTC+9")
• Time sync interval: Synchronization interval in hours (default: 24)

DHT22 Sensor Configuration

• DHT22 GPIO Pin: DHT22 data pin (default: 4)
• DHT22 read interval: Reading interval in seconds (default: 60)

Display Configuration

• SSD1306 SDA GPIO Pin: Display SDA pin (default: 12)
• SSD1306 SCL GPIO Pin: Display SCL pin (default: 14)
• SSD1306 I2C Address: I2C address (default: 0x3C)
• Display update interval: Update interval in seconds (default: 5)

2. Build

idf.py build

3. Flash to ESP8266

idf.py -p /dev/ttyUSB0 flash

Replace /dev/ttyUSB0 with your correct serial port.

4. Serial Monitor

idf.py -p /dev/ttyUSB0 monitor

Usage

After flashing and booting:

1. ESP8266 automatically connects to the configured WiFi
2. Synchronizes time with NTP server
3. Starts reading DHT22 sensor
4. Fetches weather data from OpenWeatherMap API
5. Displays on OLED:
   • Top line: Current time (left) | Indoor temperature from DHT22 (center) | WiFi indicator (right)
   • Left side: Current weather icon (large) with temperature and day of week
   • Right side: Two future forecast periods with icons, temperatures, and days of week

Display Layout

┌────────────────────────────────────┐
│ 14:35      23.5°C       [WiFi ▂▄▆█]│
│────────────────────────────────────│
│                                    │
│  ☀️              ☁️      🌧️      │
│  28°C            24°C    22°C      │
│  Sun             Mon     Tue       │
│                                    │
└────────────────────────────────────┘

Features:

• Large current weather icon (32x32 pixels) on the left
• Two smaller forecast icons (16x16 pixels) on the right
• WiFi indicator shows signal bars when connected, nothing when disconnected
• Day names displayed below each temperature (3-letter abbreviations)
• Improved cloud icon with better shape and visibility

Troubleshooting

Display not working

• Check I2C connections (SDA and SCL)
• Verify display I2C address (0x3C or 0x3D)
• Test with I2C scanner

DHT22 not reading data

• Check data pin connection
• Verify module has built-in pull-up resistor
• Wait 2 seconds after boot for stabilization

No weather data

• Check WiFi connection
• Verify API key is correct
• Check logs with idf.py monitor
• Free API tier has request limits

Incorrect time

• Check internet connection
• Configure timezone correctly in menuconfig
• Wait for NTP synchronization (may take up to 30 seconds)

Project Structure

esp8266_weather_oled/
├── CMakeLists.txt              # Root CMake file
├── Kconfig.projbuild           # Project configuration
├── README.md                   # This file
├── main/
│   ├── CMakeLists.txt
│   └── esp8266_weather_oled.c  # Main application
└── components/
    ├── wifi_manager/           # WiFi management
    ├── time_manager/           # NTP synchronization
    ├── dht22/                  # DHT22 driver
    ├── weather_api/            # OpenWeatherMap client
    └── ssd1306/                # OLED display driver
        ├── ssd1306.c           # Display initialization and layout
        ├── ssd1306_draw.c      # Drawing functions and icons
        └── ssd1306_fonts.c     # Font definitions

Component Details

WiFi Manager

• Handles WiFi connection and reconnection
• Configurable retry attempts
• Status monitoring

Time Manager

• NTP-based time synchronization
• Timezone support
• Periodic re-synchronization

DHT22 Driver

• Temperature and humidity readings
• Configurable read interval
• Error handling and retry logic

Weather API

• OpenWeatherMap 5-day/3-hour forecast API
• Parses current weather and 2 future periods
• Weather condition icons mapping
• Automatic periodic updates

SSD1306 Display Driver

• I2C communication
• Custom font with lowercase letters support
• Weather icons (normal and large size)
• WiFi signal indicator
• Drawing primitives (pixels, lines, rectangles)

License

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

Contributing

Contributions are welcome! Feel free to open issues or pull requests.

Additional Resources

• ESP8266 RTOS SDK Documentation
• OpenWeatherMap API Documentation
• SSD1306 Datasheet
• DHT22 Datasheet