It goes without saying that KNX ® is regarded as a leading protocol for building and home automation, with more than 8,000 products certified by the KNX Association, 500 member companies, alliances with almost 100,000 installation partners covering 190 countries. In fact, KNX is the only truly open and vendor-independent global standard, with around 400 million devices deployed.
The standardization of the KNX bus protocol is achieved through multiple international and regional standards combined with legacy protocols to provide a medium-independent Open Systems Interconnection (OSI) protocol. KNX can be deployed wirelessly via RF or IP, but simple twisted pairs that carry node power and data are popular for their low cost and simplicity. The similarity to telephone wiring helps to enhance familiarity with KNX wiring.
The need for interoperability
The breadth and installed base of KNX would not be possible without interoperability between products from different vendors. An extensive certification program managed by the KNX Association requires suppliers to demonstrate that products meet requirements, especially protocol features, supported profiles, network interconnections and optional features.
While testing can be tedious, it shouldn’t be a hindrance – just ensure 100% interoperability. But if a vendor intends to resell a certified product previously purchased from an association member under its own brand, then there is no need for this “derivative” or “OEM” as long as the physical layer (PHY) and software stack are present and unmodified “Product for further testing. This greatly simplifies the process and avoids involving unnecessary testing time and costs, as the product only needs to carry the KNX Product Modification Statement instead of a full compliance test.
Modular KNX solution
The first KNX pre-certified system-in-package (SiP), the NCN5140S, represents a significant step forward in expanding the adoption of KNX networks in building automation applications. The traditional way of designing a KNX network is to build a system from individual components. The NCN5140S SiP is pre-certified and requires only advanced customization without touching any underlying firmware, PHY or software stack. Ultimately custom KNX systems can be developed without the need to test and validate every variant of the system design.
ON Semiconductor’s NCN5140S contains all critical and certifiable elements, including PHY and Media Access Controller (MAC) and KNX network stack and application software. These elements are integrated into the SiP and run on an ARM ® Cortex ® -M0+ based microcontroller.
Since the KNX transceiver (PHY+MAC), network stack and application software are all pre-certified, any product developed using the NCN5140S can be considered a derivative or OEM product. The new SiP saves time and cost and reduces design risk when developing new KNX products.
Capacitive inputs can be challenging, so ON Semiconductor also provides the firmware needed to connect SiPs to this type of input. The application software and certification stack are provided as binary code programmed during assembly and then configured via Engineering Tool Software (ETS).
The SiP-based modular KNX process for the NCN5140S SiP requires three steps:
1) Program the firmware (binary file) into the ARM microcontroller
2) Configure unique network ID and application options at end of production programming
3) Use ETS database to set equipment parameters during building installation
The NCN5140S is designed for wall switches or dimmers. In most use cases, these are user interface panels used to control functions such as building lighting, heating, ventilation and air conditioning (HVAC), window control, and building access.
OEM manufacturers use SiP in their designs to set up the device during end-of-production programming. During this setup, the most important thing is to write a unique KNX network ID for the OEM manufacturer. Next, the application can configure the number of switches or touch buttons, and if these require dimming, configure the monochrome or RGB LED settings in the design.
Finally, installers can fully customize wall switches via ETS from the KNX Association. Names can be assigned, while button functions, LED behavior, status indications, timers, scene settings, and more can be customized for each building.