ESP8266 Temperature Control System

Overview

This PlatformIO project implements a web-based temperature control system using an ESP8266 microcontroller. It is designed to monitor temperature via a DS18B20 sensor and control a 433 MHz relay switch for heating or cooling. The system features a modern web interface for configuration, automatic/manual relay control, persistent settings, and NTP time synchronization. It is compatible with Home Assistant via MQTT and can be easily integrated into any smart home system.

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Features

• Temperature Sensing:
  Reads temperature from a DS18B20 sensor.

• Relay Control:
  Controls a 433 MHz relay (for heating or cooling) with both automatic (temperature/time-based) and manual modes.

• Web Interface:

  • Modern, responsive interface accessible from any browser.
  • Toggle between Auto and Manual control modes.
  • In Auto mode, relay is controlled by temperature and time schedules.
  • In Manual mode, relay can be toggled directly by the user.
  • Settings for temperature setpoint, delta, frost protection, and on/off schedules.
  • Displays current temperature, relay status, and relay switch history (last ON/OFF times and ON duration).

• Persistent Settings:
  Stores user configuration in EEPROM, minimizing writes to extend EEPROM lifespan.

• Time Synchronization:

  • Synchronizes time with NTP servers.
  • Handles daylight saving time for Berlin timezone.
  • Periodically resynchronizes every 6 hours.

• WiFi Management:
  Uses WiFiManager for easy and secure WiFi setup.

🌡️ Core Temperature Control

• Precise Temperature Monitoring
  • DS18B20 digital temperature sensor with ±0.5°C accuracy
  • Configurable temperature setpoint and hysteresis (delta)
  • Frost protection with adjustable threshold
  • Temperature filtering for stable readings

⚡ Relay Control

• Flexible Relay Operation
  • 433 MHz RF relay control (supporting both ON/OFF and toggle modes)
  • Configurable pulse duration for relay control
  • Manual override capability

🌐 Web Interface

• Modern, Responsive UI
  • Real-time temperature display
  • Toggle between Auto/Manual modes
  • Configure temperature settings and schedules
  • View system status and connection information
  • Mobile-friendly design

🤖 MQTT Integration (Home Assistant Compatible)

• Seamless Smart Home Integration
  • Publish temperature updates at configurable intervals
  • Remote control via MQTT commands
  • Secure authentication support

MQTT Topics

• Command Topic: home/temperature_control/set
  • Send JSON payloads to control the device:

    {
      "state": "ON",
      "target_temp": 22.5,
      "delta_temp": 0.5,
      "frost_protection": 5.0
    }

• State Topic: home/temperature_control/state
  • Current device state in JSON format
• Temperature Topic: home/temperature_control/temperature
  • Current temperature readings
• Availability Topic: home/temperature_control/status
  • Reports "online" or "offline" status

⏰ Smart Scheduling

• Time-based Control
  • Automatic daylight saving time adjustment
  • NTP time synchronization

🔄 System Management

• Persistent Configuration
  • EEPROM storage for settings
  • WiFiManager for easy WiFi configuration
  • System status monitoring

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🚀 Getting Started

1. Hardware Setup

Wire the components as shown below. A 4.7kΩ pull-up resistor is required between the DATA and VDD pins of the DS18B20 sensor.

ESP8266 (NodeMCU)    DS18B20         433MHz Transmitter
===============      ======         ===============
3.3V                 VDD (Red)      VCC
D4 (GPIO2)           DQ (Yellow)    DATA
GND                  GND (Black)    GND

Required Hardware:

• ESP8266 (NodeMCU, Wemos D1 Mini, etc.)
• DS18B20 Waterproof Temperature Sensor
• 433MHz RF Transmitter Module
• 433MHz Relay Switch
• 4.7kΩ Resistor
• Breadboard and jumper wires
• 5V Micro-USB Power Supply

2. Software Setup & Upload

This project is configured for PlatformIO.

1. Clone the Repository:

   git clone <repository-url>
   cd ESP8266-Temperature_Control

2. Open in VS Code: Open the project folder in Visual Studio Code with the PlatformIO extension installed.
3. Build & Upload: Use the PlatformIO controls to build and upload the firmware to your ESP8266. All dependencies listed in platformio.ini will be downloaded automatically.

3. WiFi Configuration

• On the first boot, the ESP8266 will create a WiFi Access Point named ESP-Temp-Control-AP.
• Connect to this AP with your phone or computer. A captive portal should open automatically.
• Select your home WiFi network (SSID), enter the password, and save.
• The device will restart and connect to your network. The IP address will be printed to the Serial Monitor.

4. Usage

• Find the ESP8266’s IP address from your router or the Serial Monitor.
• Open the IP address in a web browser to access the control interface.
• Use the web UI to configure temperature setpoints, schedules, and control modes.

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Dependencies

This project is built using the PlatformIO framework. All required libraries are managed via the platformio.ini file and will be downloaded automatically during the build process.

• Framework: arduino
• Libraries:
  • OneWire & DallasTemperature — For the DS18B20 sensor.
  • RCSwitch — For 433 MHz RF communication.
  • WiFiManager — For easy WiFi configuration.
  • PubSubClient — For MQTT integration.
  • Core ESP8266 libraries (ESP8266WiFi, ESP8266WebServer, EEPROM, time.h).

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Code Structure

• src/main.cpp: The main application logic.
  • setup(): Initializes hardware, loads settings from EEPROM, connects to WiFi (using WiFiManager on first run), sets up NTP, and starts the web server.
  • loop(): Handles web server clients, periodically reads the temperature, executes control logic (auto/manual), and handles NTP resynchronization.
• Web Handlers: Functions like handleRoot(), handleSettings(), etc., respond to HTTP requests.
• Control Logic: The core logic for temperature and schedule-based relay control resides within the loop().
• EEPROM Management: Functions to read and write settings, designed to minimize wear.

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Security

• The web interface is not password-protected by default. If the device is accessible from an untrusted network, it is recommended to implement authentication for the web server.

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Customization

• Pin Assignments: Modify the pin definitions at the top of src/main.cpp for different hardware layouts.
• Relay Protocol: Adjust RELAY_CODE_ON, RELAY_CODE_OFF, and other RCSwitch parameters for your specific 433 MHz relay.
• Timezone: Change the TZ_INFO string for your local timezone.

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🔌 Home Assistant Integration

To integrate this device as a generic_thermostat in Home Assistant, you can use a package file.

1. Create a file named thermostat_package.yaml in your Home Assistant packages directory.
2. Add the following content to the file, updating MQTT topics if you changed them.
3. Include the package in your configuration.yaml:

# filepath: configuration.yaml
homeassistant:
  packages:
    thermostat: !include thermostat_package.yaml

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License

This project is open source and provided as-is, without warranty.
Feel free to modify and adapt it to your needs!