KNX Bus MQTT Gateway Kit with Arduino Mega + LED
Build a KNX Bus MQTT Gateway with Arduino Mega: Bridge Legacy Building Automation to IoT
Every part needed, pre-tested for compatibility, with an AI build companion trained on this exact project. Shipped from Bengaluru in 3-5 days.
Integrate legacy KNX building systems with modern IoT dashboards. This kit lets you build a fully functional gateway that translates KNX bus telegrams into MQTT messages, enabling remote monitoring and control of lights, blinds, and HVAC in commercial or residential smart buildings. No need for expensive branded bridges—assemble, program, and deploy your own low-level protocol converter.
What You'll Build
You'll assemble a DIN-rail mountable gateway that listens on the KNX bus, decodes telegrams with the NCN5121 transceiver, and publishes device states to any MQTT broker. This enables real-time dashboards, rule engines, and mobile alerts for existing building automation installations across India, from corporate offices to university labs.
What You'll Learn
- Interfacing the NCN5121 KNX transceiver with Arduino Mega via SPI, handling bus collision avoidance and telegram acknowledgements
- Parsing and constructing KNX telegrams (EIB/KNXnet/IP) and mapping group addresses to MQTT topics
- Programming the Arduino to bridge serial protocols and publish JSON payloads over Ethernet/Wi-Fi (with separate module)
- Designing a stable power supply circuit with LM2596 buck converter to safely power the gateway from KNX bus voltage
Kit Contents
| Component | Quantity |
|---|---|
| Arduino Mega 2560 | 1 |
| NCN5121 KNX Transceiver | 1 |
| LM2596 Buck Converter | 1 |
| 0.96in OLED | 1 |
| 100nF Capacitors | 15 |
| 4.7kΩ Resistors | 5 |
| PCB Prototype Board | 3 |
| DIN Rail Enclosure | 1 |
| Soldering Iron | 1 |
| Solder Wire | 1 |
Why Buy This Kit Instead of Sourcing Parts Separately
| Factor | Sourcing Separately | Compoden Kit |
|---|---|---|
| Compatibility checks | You verify every part | Pre-tested as a system |
| Build support | Forums and scattered tutorials | AI companion trained on this exact project |
| Time to first working build | Days of debugging | Hours, with step-by-step guidance |
| Shipping coordination | Multiple sellers, multiple delays | One shipment from Bengaluru in 3-5 days |
Who This Kit Is For
Ideal for B.Tech ECE/EEE students tackling smart building integration in final-year projects or Smart India Hackathon, facility management engineers upgrading legacy KNX installations in Indian commercial buildings, and professional integrators prototyping custom MQTT bridges for automation panels. Prior experience with Arduino coding and basic electronics assembly is assumed.
Built and Backed by Compoden
Every Compoden kit ships with an AI build companion trained on this exact project — accessible via a QR code on the box, with WhatsApp and email backup. We've spent 10 years building projects for makers, schools, and institutions across India. If a part fails because of a manufacturing defect, replace it free within 7 days.
What if I get stuck during the build?
Use the AI companion’s step-by-step guidance; for tricky KNX bus timing issues, our WhatsApp support team has direct experience with the NCN5121 transceiver and Arduino libraries.
Can I connect this gateway to Wi-Fi or Ethernet for MQTT?
The kit provides the core KNX-MQTT bridge on Arduino Mega. You can attach an Ethernet shield or ESP8266 module to the Arduino’s serial/UART pins—the AI companion includes wiring diagrams for both options.
Does this kit work with existing KNX installations using ETS software?
Yes, the NCN5121 transceiver reads standard KNX telegrams; you’ll need to know the group addresses assigned in your ETS project to map them to MQTT topics. The AI companion explains how to extract that information.
What power supply does the gateway require?
The LM2596 buck converter lets you power the Arduino and transceiver directly from the KNX bus (typically 30V DC), so no separate power adapter is needed once installed in the DIN rail enclosure.
Arduino + NCN5121 KNX transceiver bridges KNX bus telegrams to MQTT for legacy building automation.
What's in this kit
- Arduino Mega 2560
- NCN5121 KNX Transceiver
- LM2596 Buck Converter
- 0.96in OLED
- 100nF Caps x15
- 4.7kΩ Resistors x5
- PCB Prototype Board x3
- DIN Rail Enclosure
- Soldering Iron
- Solder Wire
Choose your assembly option:
- Soldering Kit — 25W soldering iron, 60/40 solder wire, flux, and small perfboard for permanent assembly.
- Breadboard Combo — 800-point full-size breadboard with 65-piece jumper wire pack for solderless prototyping.
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Shipping Information
- Prepaid Orders: ₹75 for orders up to ₹999, FREE shipping above ₹999
- COD Orders: ₹125 shipping + ₹50 COD fee = ₹175 total
- Delivery Timeline: Dispatch in 1-2 days, delivery in 2-7 days depending on location
Returns & Warranty
- 7-Day Return: Manufacturing defects only (approval required)
- Warranty: 7 days from delivery
- Non-Returnable: Batteries, consumables, cut wires, clearance items