The Open Source IoT Room Thermostat project by Adam Sharp is a simplified IoT Room Thermostat that has been specifically designed to function like a traditional room thermostat to the user, but provide the functionality of a modern IoT based thermostat. Without the cost, complexities or dependencies of modern IoT thermostats that are available today.

Being Open Source, allows easy inclusion into a range of Home Automation and IoT projects (such as Home Assistant, Node Red, etc). Low cost, versatile and above all else, cost effective enough to install in every room of your home.

Based on the Seeed Xiao series of MCU modules, providing a choice of processing heart. Originally designed to use an ESP32 MCU loaded with the Tasmota firmware. The design also supports other cores and firmware, including self coded, Home Assistant and similar products.

With an included DS18B20 temperature sensor, there is additional support for a variety of four pin I2C environmental sensors. By default the SCD40 or SCD41 were designed to be the core room environmental sensor array. Providing temperature, humidity and CO2 levels. An RGB status LED is provided for user feed back. There is also a 1-wire bus connector (for additional DS18B20 semi-remote temperature sensors), 0.1” expansion header and an industry standard QWIIC interface available if needed. A suitable case is available (produced by Camdenboss) to allow a professional install to be completed with ease. Artwork is available for a panel graticule. Or you can use your own setup.

There are no control interfaces provided, as the thermostat is only designed to be an environmental monitor. All heating/cooling functionality is provided by the backend systems and connections to the relevant systems.

Being Open Source hardware all the latest hardware design files are available for your own production or modification changes. Licensed under the Creative Commons Attribution 4.0 International License. You are free to make changes as you require. However, you must attribute the original works to the original designer.

A simple 2 layer PCB design makes PCB production very cheap and simple. Through-the-hole components are used throughout, except for the MCU. But even the MCU is simple to install as an SMD for most electronic enthusiasts.

All PCB design files are available for download so you may produce your own, by hand or using a suitable fabrication facility. I may provide blank PCBs, kits, and fully assembled units at a later date.