ESP8266 Temperature Monitor v2.1.0

An advanced ESP8266-based IoT temperature and humidity monitoring system with enhanced telemetry, energy efficiency, and comprehensive error handling.

Version 2.1.0 Features

🚀 Enhanced Functionality

• Advanced Environmental Metrics: Heat index, dew point, absolute humidity, and comfort level assessment
• Intelligent Data Transmission: Only sends data on significant changes or at regular intervals
• 24-Hour Statistics: Rolling averages, min/max tracking over 24-hour periods
• Deep Sleep Mode: Ultra-low power consumption with 5-minute wake intervals
• Comprehensive Error Handling: Retry logic, connection recovery, and error tracking
• Performance Monitoring: Real-time metrics for WiFi, sensor, and API response times

📊 Telemetry Levels

• Basic Telemetry: Core sensor data and metadata (sent on significant changes)
• Full Telemetry: Complete system diagnostics (sent every 12th reading/hourly)

🔋 Power Management

• Deep sleep between readings for battery operation
• LED status indicators for operation feedback
• VCC voltage monitoring

Hardware Requirements

• ESP8266 development board (NodeMCU, Wemos D1 Mini, etc.)
• DHT22 temperature/humidity sensor
• Jumper wires
• Optional: Battery pack for portable operation

Wiring

Connect the DHT22 sensor to the ESP8266:

• VCC → 3.3V
• GND → GND
• DATA → GPIO2 (D4 on NodeMCU)

Arduino IDE Setup

1. Install the ESP8266 board package in Arduino IDE
2. Install required libraries:
   • ESP8266WiFi (included with ESP8266 package)
   • ESP8266HTTPClient (included with ESP8266 package)
   • WiFiClientSecure (included with ESP8266 package)
   • DHT sensor library by Adafruit
   • ArduinoJson by Benoit Blanchon

Configuration

1. WiFi Credentials

Update WiFi settings in esp8266_temp_monitor.ino:

const char* ssid = "YOUR_WIFI_SSID";
const char* password = "YOUR_WIFI_PASSWORD";

2. API Endpoint

Configure your API endpoint:

const char* apiEndpoint = "YOUR_API_ENDPOINT";

3. Adjustable Parameters

• SLEEP_INTERVAL: Deep sleep duration (default: 5 minutes)
• TEMP_CHANGE_THRESHOLD: Temperature change threshold for transmission (default: 5°F)
• HUMIDITY_CHANGE_THRESHOLD: Humidity change threshold for transmission (default: 10%)
• FULL_TELEMETRY_INTERVAL: Full telemetry transmission interval (default: every 12 readings)

API Specification

The OpenAPI 3.0 specification for the sensor data API is provided in sensor-api.yaml. The system supports both basic and full telemetry modes.

Data Formats

Basic Telemetry (Sent on significant changes)

{
  "sensor_data": {
    "temperature": 72.3,
    "temperature_unit": "F",
    "humidity": 45.2,
    "heat_index": 72.1,
    "dew_point": 50.8,
    "absolute_humidity": 7.9,
    "comfort_level": "comfortable"
  },
  "metadata": {
    "timestamp": 1640995200,
    "timestamp_iso": "2022-01-01T12:00:00Z",
    "local_time": "2022-01-01 07:00:00 CDT",
    "device_id": "AA:BB:CC:DD:EE:FF",
    "sensor_type": "DHT22",
    "firmware_version": "2.1.0",
    "transmission_type": "basic"
  }
}

Full Telemetry (Sent hourly)

Includes all basic data plus:

• Device Information: Chip details, memory usage, SDK version
• Power Management: VCC voltage, sleep settings
• Connectivity: WiFi quality, signal strength, network details
• Performance Metrics: Timing data, heap usage, CPU frequency
• Statistics: Success rates, error counts, 24-hour trends
• Diagnostics: Recent error history

System Features

🛡️ Reliability

• Multiple Reading Attempts: Up to 3 attempts for sensor readings
• Connection Recovery: Automatic WiFi reconnection
• Data Validation: Range checking and sanity validation
• Persistent Storage: EEPROM storage for statistics and error history

📈 Performance Monitoring

• WiFi connection time tracking
• Sensor read time monitoring
• API response time measurement
• Memory usage diagnostics

🔧 Error Handling

• Comprehensive error categorization
• Error history tracking (last 5 errors)
• Automatic retry mechanisms
• Graceful degradation on failures

💡 Status Indicators

• LED Patterns:
  • 2 quick blinks: Successful operation
  • 5 fast blinks: Error condition
  • Solid during operation

Monitoring and Diagnostics

The system provides extensive monitoring capabilities:

• Real-time Metrics: Temperature, humidity, heat index, dew point
• Environmental Assessment: Comfort level classification
• 24-Hour Trends: Rolling statistics and extremes
• System Health: Success rates, error frequencies
• Performance Data: Timing metrics and resource usage

Version History

• v2.1.0: Enhanced telemetry edition with advanced environmental metrics, deep sleep, and comprehensive monitoring
• v2.0.0: API version 2.0 with enhanced payload structure
• v1.x: Basic temperature and humidity monitoring

License

This project is open source and available under standard licensing terms.