- Introduction
- The DOMIX Manifesto
- System Architecture
- Available Modules
- PCB Composition
- Technical Specifications
- Getting Started
- DOMIX ESPHome Software
- Comparison with Other Systems
- License & Disclaimer
- Documentation, Contributing, Contact & Acknowledgments
Note
Please read the Full Technical Manual: Technical Documentation PDF to understand the project's full potential and features, below is just a summary of the project's features.
For several years, I have been managing the equipment in my home using automated systems that report all necessary information to a central controller, both for operational control and for data analysis.
These tools have only recently evolved, perhaps a decade or so for the consumer sector. Logic controllers, on the other hand, have been around for decades, but I don't think they'll easily become usable by a simple enthusiast like me, both due to their cost and their architecture.
As I've evolved my systems day by day, I've realized—unfortunately, too late, given that the learning curve for self-taught software is always very steep—that the best system, in my opinion, is always a centralized one. After experimenting with both centralized and distributed approaches, the conclusion is clear: having everything converges into a single control point offers decisive advantages.
Many commercial solutions offer hybrid approaches, but excluding well-known and expensive systems, I could not find a simple solution capable of offering everything within a single device. From this need, the DOMIX project was born combining prior experience in electronics and automation into a single coherent ecosystem.
The idea is to concentrate the control logic inside a dedicated electrical cabinet, interfacing with actuators and safety switches belonging to the main electrical panel. This cabinet is not a conventional electrical panel, but a control cabinet designed to host automation logic and low-voltage control devices. The electrical power panel is not part of the DOMIX project; it relies on qualified electricians to connect the DOMIX system to the real world.
Yes, I know what you're thinking: who knows how many wires I have to run in my house! Or: how can I modify an existing system now? Well, I agree with you, this system is ideal if you're starting from scratch. If I don't yet have any conduit or corrugated pipes inside my walls, that's true, but in my opinion, even on a small scale, it can be adapted to many situations. On the other hand, imagination is a big part of the job of those who start thinking up similar systems on their own.
By centralizing all control wiring—both inputs (buttons, switches) and outputs (actuators, relays, contactors)—the system remains organized, flexible, and ready for complex logic and future expansion.
DOMIX is an open-source, modular, DIN-rail home automation system designed for centralized control and monitoring. Born from years of personal experience with home automation, DOMIX combines the structured approach of industrial systems with the flexibility of DIY platforms.
- ✅ Fully modular DIN-rail design
- ✅ Centralized logic with decentralized I/O
- ✅ Native Ethernet + Zigbee support
- ✅ ESPHome-based programming
- ✅ Open hardware & software
- ✅ No vendor lock-in
- ✅ Low-voltage safety (12V DC max)
DOMIX is built on 10 core principles:
- Open by Design - All schematics and documentation are open source
- No Competition with Industrial Systems - Research platform, not certified product
- Research, Not Certification - Built for learning and experimentation
- Modular or Nothing - Only M1 is mandatory, everything else is optional
- Cabinet-Oriented, Low-Voltage Only - Never drives power loads directly
- Ethernet First, Always - Wired reliability over wireless dependency
- Open Ecosystem Integration - Works with Home Assistant, ESPHome, MQTT
- Zigbee as a First-Class Citizen - Native Zigbee coordinator capability
- Fully Customizable by Design - Firmware and logic can be freely modified
- Built for People Who Want to Understand - Transparency over abstraction
Important
DOMIX exists because building things is still fun. If it teaches something, it has succeeded.
DOMIX uses a centralized core (M1) with specialized I/O expansion modules connected via I2C bus. All modules mount on standard 35mm DIN rail.
- Power & Data: 8-pin IDC flat cables
- I2C Bus: Two independent buses (expandable to 8 with M1 v1.1)
- Communications: Ethernet (primary), Zigbee, RS485
The system carefully manages I2C address space across three ranges:
| Range | Used For | Max Devices |
|---|---|---|
| 0x20–0x27 | PCA9554A, PCA9535 | 8 |
| 0x38–0x3F | PCA9554A, PCF8574, PCA9535 | 8 |
| 0x48–0x4B | ADS1115 (ADC) | 4 |
| Module | Function | DIN Width | Description |
|---|---|---|---|
| M1 | Core/Gateway | 4 modules | ESP32-S3, Ethernet, Zigbee, RS485, I2C hub |
| Module | Function | DIN Width | I/O Count | Description |
|---|---|---|---|---|
| M2 | General I/O | 2 modules | 8 in / 8 out | Optocoupled inputs, Darlington outputs |
| M3 | Door/Window Contacts | 2 modules | 16 analog in | Analog multiplexer for reed switches |
| M7 | Digital Output | 2 modules | 16 out | General purpose 12V outputs |
| M8 | Digital Input | 2 modules | 16 in | General purpose optocoupled inputs |
| Module | Function | DIN Width | Relays | Description |
|---|---|---|---|---|
| M4 | 6-Relay | 2 modules | 6 | 10A @ 250VAC relays |
| M5 | 12-Relay | 4 modules | 12 | 10A @ 250VAC relays |
| Module | Function | DIN Width | Description |
|---|---|---|---|
| M6 | Energy Meter | 4 modules | 10-channel current clamp meter |
| M9 | Sprinkler Controller | 4 modules | 8-zone sprinkler control with 24VAC output |
The DOMIX sensor family consists of a shared S Core board combined with interchangeable sensor daughter boards designed for different installation scenarios and use cases. The S Core is always required and is identical across all configurations; only the daughter board and the 3D-printed enclosure change. Not all sensors need to be populated on any given board — every component is independently optional and the final build is entirely up to the user.
There are four possible configurations arising from two independent choices: installation type (ceiling or wall 503-box) and sensor/interface trade-off within each form factor.
| Configuration | Installation | LD2410C | PIR | BME280 | SCD41 | SGP41 | BH1750 | OLED + Encoder | IR TX | IR RX |
|---|---|---|---|---|---|---|---|---|---|---|
| S Core + S1a | Ceiling – mmWave | ✓ | – | ✓ | ✓ | ✓ | ✓ | – | ✓ | ✓ |
| S Core + S1b | Ceiling – PIR | – | ✓ | ✓ | ✓ | ✓ | ✓ | – | ✓ | ✓ |
| S Core + S2a | Wall 503 – Display | ✓ | – | ✓ | – | ✓ | – | ✓ | – | ✓ |
| S Core + S2b | Wall 503 – Sensors | ✓ | – | ✓ | ✓ | ✓ | ✓ | – | – | ✓ |
✓ = included in this variant – = not available in this variant
Choosing the right variant:
- S1a / S2a (mmWave) — best for living rooms and bedrooms where detecting stationary presence matters (e.g. someone sitting and reading). The LD2410C radar detects static occupancy reliably where PIR cannot.
- S1b (PIR) — simpler and lower cost, adequate for corridors, entrances, or secondary rooms where motion detection is sufficient.
- S2a (Display) — ideal when local interaction is needed, such as a wall-mounted thermostat or a room controller with manual input via the rotary encoder. Trades SCD41 and BH1750 for the OLED + encoder interface.
- S2b (Sensors) — best for rooms where air quality monitoring is the priority (bedroom, home office, kitchen): adds CO₂ (SCD41) and light (BH1750) on top of temperature, humidity, and VOC.
All configurations share the same S Core: RP2040 microcontroller, USB-C programming, 12V power input, and RS485 communication back to the DOMIX M1.
Each DOMIX module is not a single PCB but a stack of multiple boards that snap together via IDC flat cables. Understanding which boards make up each module helps you know what to order, build, and assemble.
The boards are divided into three roles:
- Vertical Module — carries power and I2C bus connectors.
- Display Module — an optional front-facing board with the OLED screen and encoder/button interface.
- Functional Module — the core board specific to each module's purpose (I/O, relay, energy metering, etc.).
Some boards are shared between multiple module numbers to reduce design complexity and PCB variants.
| Module | Vertical | Display | Functional Board(s) | Notes |
|---|---|---|---|---|
| M1 | Middle Module v1.0 + v1.1 | Display Module | Core Module | Middle module acts as mid-layer between core and vertical; v1.1 adds second I2C multiplexer |
| M2 | Vertical Module | Display Module | I-O Module | 8 in / 8 out general I/O |
| M3 | Vertical Module | Display Module | Contact Module | 16-channel analog contact reader |
| M4 | (shared M3-4) | (shared M3-4) | 6 Relay Module | Vertical and display boards are shared with M3 |
| M5 | (shared M3-4-5-6) | (shared M5-6) | 12 Relay Module | Vertical shared across M3/M4/M5/M6; display shared with M6 |
| M6 | (shared M3-4-5-6) | (shared M5-6) | Energy Meter Module | Same vertical and display as M5 |
| M7 | Vertical Module | Display Module | Output Module | 16 digital outputs |
| M8 | Vertical Module | Display Module | I-O Module | 16 digital inputs (same I-O board as M2, different config) |
| M9 | Vertical Module | Upper Module | Sprinkler Module | Upper Module replaces the display, handles 24VAC switching |
Shared boards explained: The label
M3-4on a board means that PCB is used in both M3 and M4. SimilarlyM3-4-5-6is a single vertical design that fits M3 through M6, andM5-6is a display shared between M5 and M6. This reduces the number of unique PCB designs without limiting functionality.
The sensor family follows a core + daughter board approach. The S Core is always present; the S1 or S2 board changes depending on installation type.
| Board | Role | Description |
|---|---|---|
| S Core | Main board | RP2040 MCU, RS485, USB-C, 12V input — identical in every sensor node |
| S1 | Daughter board | Ceiling form factor — fits LD2410C (mmWave) or PIR depending on variant |
| S2 | Daughter board | Wall 503-box form factor — fits OLED+encoder or additional sensors depending on variant |
Each sensor node = 1× S Core + 1× S1 or S2 daughter board, housed in a dedicated 3D-printed enclosure.
- MCU: ESP32-S3-WROOM-1-N8R2 (dual-core, Wi-Fi, USB-C)
- Ethernet: W5500 controller, 10/100 Mbps
- Zigbee: RF-BM-2652P2 (TI CC2652, external antenna)
- RS485: MAX13487E transceiver with TVS protection
- Power: 9-12V DC input, 5V/3.3V internal rails
- I2C: 2 buses (expandable to 8 with TCA9548A)
- Display: Optional 1.3" OLED (128×64, SH1106)
- System Logic: 3.3V @ <500mA
- Relay Coils: 5V (total system max 2A)
- External Control: 12V DC
- PCB Layers: 2-4 layer depending on module
- Enclosure: 3D-printed, standard DIN dimensions
- Connection: IDC flat cables (1mm pitch)
- Terminals: Removable screw blocks (max 1.5mm²)
- Basic electronics knowledge
- Soldering skills
- 3D printer (for enclosures)
- ESPHome environment
- 12V DC power supply
-
Minimum Configuration:
- 1× M1 Core module
- 12V DC power supply
- Ethernet cable
-
Recommended Starter Kit:
- 1× M1 Core
- 2× M2 General I/O
- 1× M4 6-Relay
- Power supply + cables
-
Assembly Steps:
- Configure I2C addresses on expansion modules
- Program ESP32 via USB-C with ESPHome
- Flash Zigbee firmware to RF-BM-2652P2
- Connect modules with IDC cables
- Mount on DIN rail
Critical: Plan addresses before assembly to avoid conflicts.
Example configuration:
M1: Core (no address)
M2 #1: 0x20
M2 #2: 0x21
M4: 0x38
M3: 0x39 + ADS1115 @ 0x48
Check section 4.4 of manual for detailed address planning guidelines.
ESPHome firmware for the DOMIX modular home automation system.
DOMIX is split into two independent firmware targets:
- M — Cabinet controller (ESP32), manages I/O modules, relays, shutters, energy metering and communicates with sensor nodes via RS485/Modbus RTU.
- S — Room sensor node (RP2040), collects environmental data (temperature, humidity, CO₂, VOC, presence…) and exposes it to the M controller over Modbus RTU.
Both targets follow the same workflow:
- Edit
hardware/data.yaml— set your device name, network/MQTT credentials, I2C addresses and Modbus address. This is the only file you need to touch before compiling. - Edit
main.yaml— comment out any hardware module or sensor not physically present. - Flash via USB-C:
esphome run M/main.yamloresphome run S/main.yaml. Subsequent updates of M1 module can be done OTA, S module have to be programmed only via USB-C.
- Modular architecture — include only what you install.
- Wired Ethernet (W5500), MQTT, OTA updates, OLED display and button menu on the M1.
- Room sensors: BME280, BH1750, SCD41 (CO₂), SGP41 (VOC/NOx), LD2410 mmWave radar, PIR, IR transceiver.
- RS485/Modbus RTU link between M and S nodes (one
modbus_master.yamlinclude per room). - Optional Zigbee coordinator (CC2652) — requires ESPHome ≤ 2025.x.
Software/
├── M/ # Cabinet controller firmware (ESP32)
│ ├── hardware/ # Board, Ethernet, MQTT, I2C, OTA, screen…
│ ├── module/ # One file per expansion module (M1–M9)
│ └── sensor/ # DS18B20 wire sensor + Modbus master template
└── S/ # Room sensor node firmware (RP2040)
├── hardware/ # Board, I2C, Modbus slave…
├── sensor/ # BME280, BH1750, SCD41, SGP41, LD2410, PIR, IR…
└── font/ # OLED fonts
Full wiring, register map, MQTT topic convention and menu reference are documented in the extended README.
Warning
ESPHome version 2026 is not compatible with the external Zigbee component, so if you need to use it you must compile it with a maximum version of 2025. I used 2025.7.5. If you don't need it, you can use the latest version.
The RF-BM-2652P2 module requires Z-Stack firmware. See POE Zigbee Coordinator for flashing instructions.
- Home Assistant: MQTT/Native API
- Node-RED: MQTT broker
- OpenHAB: MQTT binding
- Custom: Direct ESPHome API
| Feature | DOMIX | KNX | Shelly/Sonoff | Industrial PLC |
|---|---|---|---|---|
| Architecture | Centralized core | Fully distributed | Device-based | Centralized |
| DIN Rail | Native | Yes | Partial | Yes |
| Programming | ESPHome (open) | ETS (licensed) | App/Cloud | Vendor IDE |
| Vendor Lock-in | None | High | Medium-High | High |
| Entry Cost | Low-Medium | High | Low | Very High |
| Wireless | Zigbee native | Optional | Wi-Fi | Rare |
| Certification | None (research) | Full | Consumer | Industrial |
✅ You want full control over firmware and logic
✅ You prefer wired reliability
✅ You need clean DIN-rail cabinet integration
✅ You want to understand and customize your system
✅ Energy monitoring is important
✅ You need multi-sensor room monitoring (air quality, presence, light, IR) in a single node
❌ Formal building certification required
❌ Extremely large installations (100+ nodes)
❌ Plug-and-play is the primary goal
❌ Production environment without validation
Version: 1.3
Last Updated: April 2026
DOMIX © 2026 by carletz
Licensed under CC BY-NC-SA 4.0
- ✅ Attribution required
- ✅ Share Alike - derivative works must use same license
- ❌ Non-Commercial - commercial use not permitted
- ✅ Modifications and derivatives allowed
This project is provided as-is for educational and experimental purposes.
⚠️ Not certified for production use⚠️ All electrical connections must be done by qualified personnel⚠️ No warranties or guarantees provided⚠️ User assumes all risks
Always follow local electrical codes and safety regulations.
- Full Manual: Technical Documentation PDF
- Schematics, Gerbers, Pick and place and Interactive BOM: Available in each module directory
- BOM: Available in BOM directory
- 3D Models: Available in 3D Print files directory
- ESPHome Examples: Available in Software
Contributions are welcome! Please:
- Fork the repository
- Create a feature branch
- Commit your changes
- Open a pull request
- GitHub Issues: For bug reports and feature requests
- Oshwlab Stars 2026 Page: DOMIX
- Related Projects:
- ESPHome community
- Zigbee2MQTT / Z-Stack firmware by Koenkk
- Zig Star for Zigbee tools
Built with curiosity. Shared with transparency. Used with responsibility.
If DOMIX teaches you something, it has succeeded. ✨