weatherstation/README.md

ESP32 Weather Station

A comprehensive weather monitoring system built on ESP32 with multiple sensors and MQTT connectivity for IoT integration.

Features

• Temperature and humidity monitoring (DHT11)
• Atmospheric pressure measurement (BMP180)
• Rain detection sensor (analog)
• Light detection (LDR) with LED indicator
• Real-time 16x2 I2C LCD display
• WiFi connectivity with automatic reconnection
• MQTT data publishing with JSON format
• Automatic MQTT reconnection with random client ID
• Non-blocking timer-based sensor readings
• Error handling and status indication
• Serial debugging output (115200 baud)

Hardware Requirements

• ESP32 development board
• DHT11 temperature/humidity sensor
• BMP180 pressure sensor
• Rain sensor module (analog output)
• LDR (Light Dependent Resistor)
• 16x2 I2C LCD display (0x27 address)
• LED (for light status indication)
• Breadboard and jumper wires

Software Dependencies

• DHT sensor library
• LiquidCrystal I2C
• SFE BMP180 Breakout Library
• PubSubClient

Configuration

Update the following constants in weatherstation.ino:

• ssid: Your WiFi network name
• password: Your WiFi password
• mqtt_server: Your MQTT broker address
• mqtt_port: MQTT broker port (default 1883)
• mqtt_topic: MQTT topic for data publishing (default: weather/station)

Pin Configuration

• DHT11 Sensor: Pin 4
• LDR Sensor: Pin 35 (input only)
• Rain Sensor: Pin 34 (analog)
• Status LED: Pin 2
• I2C LCD (SDA): Pin 21
• I2C LCD (SCL): Pin 22

MQTT Data Format

The station publishes JSON data to the configured topic:

{
  "temperature": 23.45,
  "humidity": 67.89,
  "pressure": 1013.25,
  "rainLevel": 15,
  "lightDetected": true
}

LCD Display Format

Line 1: T:23.4C H:67%
Line 2: R:15% P:1013

Serial Output Format

Temp: 23.45°C, Humidity: 67.89%, Rain: 15%, Pressure: 1013.25 hPa, Light: YES

Installation

1. Install PlatformIO
2. Set up MQTT broker (Mosquitto, HiveMQ, AWS IoT, etc.)
3. Connect hardware according to pin configuration
4. Update WiFi and MQTT credentials in sketch
5. Run pio run to build
6. Run pio run --target upload to flash
7. Run pio device monitor to view serial output
8. Subscribe to MQTT topic to receive weather data

MQTT Broker Setup

1. Install Mosquitto broker or use cloud service
2. Configure broker for client connections on port 1883
3. Create topic structure: weather/station (or custom)
4. Test broker connectivity with MQTT client tools
5. Configure firewall if using local broker
6. Verify broker allows anonymous connections or add authentication

Operation Schedule

• Sensor readings: Every 2 seconds (2000ms)
• MQTT data publishing: Every 30 seconds (30000ms)
• LCD display updates: Every 2 seconds
• LED status updates: With each sensor reading
• WiFi connection attempts: 20 attempts (10 seconds timeout)
• MQTT reconnection: Every 5 seconds if disconnected

Troubleshooting

• Sensor errors: Check wiring connections and power supply
• WiFi connection: Verify SSID and password credentials
• MQTT connection: Ensure broker is accessible and running
• LCD display: Check I2C address (default 0x27) and connections
• DHT11 readings: Look for NaN values in serial output
• BMP180 sensor: Verify initialization and I2C connection
• Rain sensor: Check analog pin assignment (Pin 34)
• LDR/LED: Verify digital pin assignment (Pin 35 for LDR, Pin 2 for LED)

Code Architecture

• Modular design: Separate functions for each sensor
• Non-blocking operations: Timer-based without delays
• Structured data: WeatherData struct for sensor values
• Error handling: Validation and status reporting
• Automatic recovery: WiFi and MQTT reconnection logic

Technical Specifications

• Microcontroller: ESP32 (Dual Core, 240MHz)
• Memory: 520KB SRAM, 4MB Flash
• Wireless: WiFi 802.11 b/g/n
• Sensors: DHT11 (±2°C, ±5%RH), BMP180 (±1hPa), Rain sensor, LDR
• Display: 16x2 Character LCD with I2C interface
• Power: 5V via USB or external supply
• Communication: I2C, WiFi, MQTT

Schematics and Wiring

Quick Reference Diagram

ESP32 Weather Station Wiring
┌─────────────────────────────────────┐
│ ESP32                              │
│ ┌─────┐ ┌─────┐ ┌─────┐ ┌─────┐   │
│ │GPIO2│ │GPIO4│ │GPIO21│ │GPIO22│   │
│ │ LED │ │DHT11│ │ SDA │ │ SCL │   │
│ └─────┘ └─────┘ └─────┘ └─────┘   │
│ ┌─────┐ ┌─────┐                     │
│ │GPIO34│ │GPIO35│                     │
│ │Rain │ │ LDR │                     │
│ └─────┘ └─────┘                     │
└─────────────────────────────────────┘

Complete Wiring Guide

• DHT11 Sensor: Pin 4 (Data), 3.3V, GND
• BMP180 Sensor: SDA→GPIO21, SCL→GPIO22, 3.3V, GND
• Rain Sensor: AO→GPIO34, 3.3V, GND
• LDR: GPIO35 with 10kΩ pull-down, 3.3V
• LED: GPIO2 with 220Ω resistor, GND
• LCD Display: SDA→GPIO21, SCL→GPIO22, 5V, GND

Detailed Schematics

For complete circuit diagrams, component layouts, and assembly instructions, see schematics.md.

Bill of Materials

• ESP32 Development Board
• DHT11 Temperature & Humidity Sensor
• BMP180 Pressure Sensor
• Rain Sensor Module (analog)
• LDR (Light Dependent Resistor)
• 16x2 LCD Display with I2C Module
• LED (5mm) + 220Ω resistor
• 10kΩ resistor (for LDR)
• Breadboard and jumper wires