Tsvetan Usunov Plans a €20 Open Source Smart Home Server Solution: Meet the Olimex-HoT

Tsvetan Usunov, founder of Bulgarian open-hardware specialist Olimex, has presented at the FOSDEM conference on a project to build a resource-light equivalent to Home Assistant designed to run on hardware costing as little as $25: Olimex-HoT, the Home of Things.

"TuxCon is a local Bulgariant FOSDEM-like conference for open-source hardware and software, held in Plovdiv where we are based," Usunov explains in his presentation on the project. "When TuxCon 2025 was running, I was trying to learn Home Assistant — and I realized that there is no low-cost and easy-to-use solution for IoT [Internet of Things]. I thought that this is a good challenge. This is how the €20 Smart Home Server idea came up."

The core driving principle behind Olimex-HoT is that cloud-powered services lack privacy and lock functionality behind expensive subscriptions while open source equivalents like Home Assistant and OpenHAB are resource-hungry as they seek to compete with each other on features and flexibility. "I wanted to build something affordable and basic," Usunov explains," with a focus on simple configuration, an intuitive interface, and ease of use. Completely open-source, both hardware and software. Supporting digital and analog inputs and outputs [as well as] text inputs and outputs."

That idea would become the Olimex Home of Things, complete with a custom server built on the Allwinner T113-S3 system-on-chip with two Arm Cortex A7 cores running at up to 1GHz, 128MB of DDR3 memory, and 128MB of SPI flash — a fraction of the hardware required to run Home Assistant, coming at a time when RAM prices are skyrocketing thanks to insatiable demand from companies involved with the AI bubble. Despite targeting a retail price of just €20, the board includes wired Fast Ethernet with optional Power-over-Ethernet (PoE) support, a radio with support for Wi-Fi, Bluetooth, Zigbee, Thread, Matter, and ESP-NOW, support for lithium-polymer batteries, and a microSD Card slot for log data.

"We use OpenWRT [software]," Usunov says of the server side, "[which] runs comfortably in 128MB of RAM. [On the node side] we decided to use ESPHome because it is very popular and actively developed, supportive of a wide range of sensors and peripherals, easy to modify and extend, [and] able to run on virtually every [Espressif] ESP32 [microcontroller]. The basic functionality is already implemented. We are adding new features on a weekly basis, and plan to complete the project by the next TuxCon where we will report on the results."

Usunov's full presentation is available on the FOSDEM website and is embedded above; the slide deck is available on Slideshare.