CYD ThermostatA smart thermostat on a $15 touchscreen.
Firmware for the ESP32 “Cheap Yellow Display”. A touch UI, weekly schedules, weather-compensated heating that tunes itself, and a local web app with no cloud account needed.
Both demos run entirely in your browser against a simulated room. Nothing is sent anywhere.
Everything a thermostat should do
Built for slow underfloor heating, and works with any on/off heating relay.
Smart heating
Weather-compensated, predictive duty-cycle control using live outdoor temperatures from Open-Meteo.
Auto-tuning
Learns your home’s heat loss and thermal lag from its own history, then recommends or applies better parameters.
Weekly schedules
Up to six changes per day, Auto/Manual modes, boost and frost protection, with automatic DST handling.
7-day history
Indoor, outdoor, target and heating stored in flash, viewable on the screen and as an interactive web chart.
Local web app
Password protected and paired with a code shown on the screen. Has full settings, schedules and OTA firmware updates.
Open integrations
Optional MQTT for Home Assistant or Node-RED, plus a documented JSON HTTP API. °C or °F.
The web app, live
The thermostat serves this app on your local network. Here it talks to a simulated device: change the target, edit the schedule, browse the history or apply an auto-tune recommendation.
Open full screen ↗Under the hood
Built by M TWELVE
Embedded Systems & HMI development. This thermostat is a showcase of what we design and build: ESP32 firmware, touchscreen user interfaces with LVGL, connected devices with local web apps, and control algorithms that learn from real data.
Need firmware or an HMI for your product? Let’s talk.
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