Platform-Independent Stack
One KNX stack for STM32 and ESP. HAL or bare-metal, your choice β port to new hardware without touching your application logic.
Open Platform Β· No paywall
KNX CERTIFIED PROTOCOL STACK & FRAMEWORK DOWNLOAD FREE Β· BUILD TODAY Β· PAY WHEN YOU SHIP
- KNX Certified
- stack, by the KNX Association
- HAL + bare-metal
- STM32 Β· ESP and beyond
- β¬10,000
- license fixed for life
About Us
Start Building Today, Pay When You Ship
Kbox-UniStack is an open KNX development platform β a platform-independent protocol stack and framework. Download it, run it on STM32 or ESP, and build your product with no paywall in your way. You license it only when your product reaches KNX certification.
Platform-Independent by Design
Runs on STM32, ESP and beyond, on HAL or bare-metal. One stack, one application layer β port it to your hardware without rewriting your application.
Zero-risk start
You don't buy a licence to evaluate. Download, prototype and build your product β payment only enters the picture when you go commercial.
KNX Secure & Memory-Optimized
KNX Secure is built in, on a stack certified by the KNX Association, with a footprint tuned for constrained flash and RAM. Your product's own certification starts from proven ground.
Stack + Framework
Platform Features
KNX Secure Built In
Authenticated and encrypted KNX communication out of the box. Ship devices that meet modern security expectations β no bolt-on required.
Optimized Footprint
Engineered for constrained devices. A lean flash and RAM footprint leaves room for your application, even on small microcontrollers.
Docs and example projects
Buildable, flashable example projects you can copy as your skeleton, a porting guide and a full API reference β the documentation covers it end to end.
KNX Certified Protocol Stack
Certified by the KNX Association: System B profile with KNX Data Secure. Link, transport, network and application layers, cEMI and raw TP frame handling, and type-safe DPT encode/decode.
No Paywall to Start
Download free and build today. You pay nothing until your product goes commercial β then license at certification, at a price fixed for life.
Testing & CI/CD
Start testing before the hardware arrives.
Kbox-UniStack is not just a protocol stack β it ships ready-made, tested classes for peripherals like UART, I2C, Button, Watchdog, Flash and LED. Every one sits behind an interface, so you can verify your application logic without hardware.
Maintainable, testable code
Every peripheral sits behind an interface. Swap in a mock or fake and test your application logic deterministically, independent of hardware.
CI/CD ready
The example projects ship GoogleTest host (PC) tests. They run without ARM hardware, so you can execute them in your automated pipeline on every commit.
No drivers written from scratch
Each interface has a Base class that absorbs most of the work: ring buffers, blink state machines, counters, bookkeeping. You write only the few lines that touch the hardware.
| Interface | Base gives you | You write |
|---|---|---|
IBusDriver | TX/RX ring queues, Work() pump, inter-byte timing | Init, AvailableForTx, Transmit |
IClock | full ms/second counter | call Tick() from a 1 ms ISR |
IWatchDog | enabled flag + Enable/Disable/IsEnabled | Reset() (the kick) |
IFlash | address bookkeeping + 1024-byte page size, Get* | read/write/erase/lock |
ILed | blink state machine off IClock | writePin, togglePin |
IButton | callback storage + dispatch | wire GPIO IRQ to OnInterupt() |
ITransmitter | holds the IBusDriver& | Init, SetIndividualAddress |
Transparent Pricing
No Paywall. Pay When You Ship.
Most stacks make you pay just to start building. We don't. Download free, develop your product, and license only when it reaches KNX certification.
Start Developing
Download, install and build. Not a cent until your product goes commercial.
β¬0to get started
Stack License
Paid at KNX certification. Use it as much as you want, however you want.
β¬10,000one-time
Per OEM Customer
Predictable as you scale to more OEM partners.
β¬1,000per OEM customer
These prices are guaranteed for life β they will not change.
Comparable licenses run up to β¬30,000 elsewhere β and there you pay before you even start building.
FAQ
Frequently Asked Questions
Is Kbox-UniStack open source?
The source code is closed, but downloading and building with Kbox-UniStack is completely free. Think of it as an open platform: you pay nothing until your product goes commercial. Licensing kicks in only at the KNX certification stage.
Which platforms and MCUs does it support?
The core is platform-independent by design β HAL or bare-metal, with no heap allocation. STM32 works today: the prebuilt archive targets Cortex-M3 / STM32F103xB and ships with HAL examples. ESP32 support is arriving very soon, and further MCUs are being added in turn. If your target isn't on the list yet, ask β we do target-specific builds on request.
How much does it cost?
Free to download and develop. When your product reaches certification, the stack license is β¬10,000 one-time, plus β¬1,000 per OEM customer. These prices are guaranteed for life. Comparable licenses run up to β¬30,000 elsewhere β and there you pay before you even start.
Does Kbox-UniStack support KNX Secure?
Yes. KNX Secure is built in, providing authenticated and encrypted KNX communication out of the box, with a footprint optimized for constrained flash and RAM.
Can I test without hardware?
Yes. Every peripheral sits behind an interface, so you can inject mocks or fakes. The example projects ship GoogleTest host (PC) tests that run deterministically without ARM hardware β which means you can run them in your CI pipeline too.
Do I get the source code when I license it?
No β and you don't need it. Kbox-UniStack ships as a prebuilt static library plus public headers: your project includes the Stack headers and links the archive. You are free to build, ship and sell your product on top of it; only the stack's own source stays closed.
What does the β¬10,000 cover, and are there limits?
The stack licence itself, paid once when your product reaches KNX certification, plus β¬1,000 per OEM customer. There is no time limit and no per-device royalty β use it in as many devices as you want, however you want. These prices are guaranteed for life.
Do I need an RTOS?
No. Kbox-UniStack is built for a bare-metal super-loop: you call Work() once per main-loop iteration and it drains the RX queue, drives TX and runs your logic. Process() is there if you want finer-grained control. It sits on your vendor HAL or directly on bare metal.
Which KNX media are supported β TP1, IP, RF?
Twisted pair (TP1) today. The certification profile is a KNX TP1 end-device, System B (mask 07B0h), with KNX Data Secure in S-Mode. KNXnet/IP is not supported and there is no RF support β if you need IP or RF, talk to us before you start.
At KNX certification, what does the stack cover and what is on me?
Kbox-UniStack itself is certified by the KNX Association, so you start from proven ground β but your product still goes through its own KNX certification. The stack brings the mechanism: System B, KNX Data Secure S-Mode, the property model, serial-number and FDSK handling. You bring the product-specific values β your unique serial numbers, hardware type code, your DPT definitions, and key generation and labelling. The documentation has the full stack-versus-integrator table.
Start building today.
Download free and build your product. You pay only at KNX certification β β¬10,000, fixed for life.