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About

This adapter is designed to connect an OpenTherm compatible boiler to any TTL port (TTL-USB, ESP8266, ESP32, Arduino, etc).

Same size as popular RS485-TTL module for more compatibility.

As software part you can use:

• OpenTherm gateway for HomeAssistant - very intelligent OT control firmware 🧠
• Tasmota OpenTherm - perhaps the easiest way to connect the boiler to your smart home system 🏚
• Opentherm IO library for Arduino or OpenTherm Arduino/ESP8266 Library (slave mode only)
  if you want to build your own firmware 🛠

Overview

Photos

Schematic

Where to buy?

DIY

• iBOM page 🌍
• Gerber zip 🗂

This work is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License

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Inspired by

• Laxilef - OpenTherm gateway for HomeAssistant
• Schelte Bron - Opentherm Gateway
• jpraus/arduino-opentherm
• Ihor Melnyk - OpenTherm Adapter
• Tasmota OpenTherm