Olimex HoT (Home of Things) is a lightweight Smart Home solution designed to run on low-end hardware (128MB RAM, 128MB flash) and interface with nodes running ESPHome. It can serve as an easier-to-use alternative for people who don’t need all the bells and whistles provided by powerful home automation frameworks such as Home Assistant or OpenHAB.
Home Assistant open-source home automation software is great, but it requires a system with at least 2GB of RAM, and 4GB of RAM is often recommended for most users. There’s also a steep learning curve. This is what Tsvetan Usunov, Olimex CEO, realized last year when he tried Home Assistant, and he decided to start working on a low-cost, easy-to-use solution for IoT and Smart Home applications. That’s why the Olimex HoT project was created. Tsvetan gave a talk about the project entitled “Designing EUR 20 Open Source Hardware running Free/Libre Open Source Software IoT home server” at FOSDEM 2026. We now have more details, so let’s dive into it.
The hardware – T113-OlinuXino server board and ESP32-C6 nodes
Olimex is primarily a hardware company, so they designed the T113-OLinuXino board to run OpenWrt and Olimex-HoT with the goal of offering it for about 20 Euros.
T113-OLinuXino specifications:
- SoC – Allwinner T113-S3
- CPU – Dual-core Arm Cortex-A7 @ 1.2 GHz with 32 KB L1 I-cache + 32 KB L1 D-cache per core, and 256 KB L2 cache
- DSP – Single-core HiFi4
- VPU – H.265/H.264 video decoding up to 1080p60 and JPEG/MJPEG video encoding up to 1080p60
- Memory – 128 MB DDR3
- Storage
- 128MB SPI flash
- MicroSD card slot for logging
- Display Interface – MIPI LCD connector
- Audio – 3.5mm audio jack
- Networking and wireless
- 10/100Mbps Ethernet RJ45 port with optional PoE support
- 802.11b/g/n 1T1R WiFi 4 and Bluetooth 4.2 via RTL8723BS module
- Optional support for ESP-NOW, Zigbee, Thread, and Matter (I assume via the USB-A port. [Update: UEXT is another option, see comments section])
- USB – USB Type-A port
- Expansion – UEXT connector
- Power Supply
- 5V via USB-C port
- Lipo battery charger and step up for UPS functionality
- Dimension – TBD
Besides the server, you’ll also need IoT nodes, and for this, Olimex selected the existing ESP32-C6-EVB board with four relay outputs, four digital inputs, a UEXT connector, and WiFi 6, Bluetooth 5.0 LE, Zigbee, Thread, and Matter connectivity. You can see it below connected to a MOD-BME280 UEXT module with a BME280 humidity, temperature, and pressure sensor.
The Software – OpenWrt OS, Olimex HoT, and ESPHome firmware
OpenWrt memory and storage requirements have increased in recent years, but 128MB of RAM and 128MB of flash are still plenty enough. That’s what the T113-OLinuXino board is running, with the latest Linux kernels, up-to-date security updates, and various preinstalled packages for Python 3, PHP 8.0, nginx, MQTT (Mosquitto), and more.
It’s not been upstreamed yet, but Zoltan Herpai (wigyori) has ported OpenWrt to the Allwinner T113-S3, and you’ll find the source code on GitHub. The server also runs the Olimex-HoT (Home of Things) with basic functionality implemented, and accessible from a web browser using the URL olimex-hot.local.
You’ll first go through a “First run” wizard to set the timezone, connect the server to your network, and create a new user. After that, you can add a new IoT device, and the interface will show a list of parameters similar to entities on Home Assistant, and a dashboard with sensor data, toggle switches to control the relay, etc…
You’ll notice the “Not secure” warning in the screenshots above, and that’s because SSL is part of the to-do list, which also includes adding support for logs and charts, a scene editor, triggers, and push notifications. The project is progressing nicely, but the software code has not been released just yet. The plan is to “complete the project”, which I assume means publish the first release, by the next TuxCon in Bulgaria, probably in May 2026.
The firmware simply relies on the ESPHome project, which should run on most ESP32 hardware nodes. Olimex pushed a PR to ESPHome last July to fix an MQTT bug, but it has not been merged just yet. So users need to add the following lines to their YAML configuration file:
|
1 2 |
external_components: - source: github://pr#9315 |
There’s also one small problem on the server side. The RTL8723BS/RTL8723DS driver only supports monitoring mode, so Olimex relied on an AR9721 USB WiFi dongle during development.
It might be a timely project, now that the price of RAM and electronic components as a whole is going up significantly, although the IoT server itself should only be a small part of the cost of a Smart Home setup. For more details, visit the project’s GitHub repository (only PDF schematics for now) and check out the slides and presentation video recording on the FOSDEM website.
Jean-Luc started CNX Software in 2010 as a part-time endeavor, before quitting his job as a software engineering manager, and starting to write daily news, and reviews full time later in 2011.
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