KNX to MQTT Gateway Kit with Arduino Mega & OLED
Seamlessly Connect Legacy KNX Buildings to Modern MQTT Networks with Arduino Mega
Every part needed, pre-tested for compatibility, with an AI build companion trained on this exact project. Shipped from Bengaluru in 3-5 days.
Thousands of commercial buildings and housing societies across India run on KNX bus systems installed over a decade ago. Facility managers now need to bring that legacy infrastructure into modern IoT dashboards, energy analytics platforms, or BMS software that speaks MQTT. This kit gives you a complete, solder-ready gateway that listens to KNX telegrams and relays them as structured MQTT topics - turning a closed bus into an open data stream.
What You'll Build
You will assemble a DIN-rail mountable gateway that sits on a live KNX bus, decodes telegrams using an NCN5121 transceiver, and publishes switch states, sensor readings, and actuator feedback to any MQTT broker. The on-board OLED shows bus health, device counts, and message throughput in real time, so you can confirm the physical KNX wiring is correct before going digital.
What You'll Learn
- How to power and bias a KNX transceiver using an LM2596 buck converter from a standard 24V bus supply
- Parsing raw KNX telegram frames with Arduino Mega and mapping group addresses to human-readable topics
- Implementing an MQTT client library on an ATMega2560 that keeps a persistent connection to a broker while handling bus interrupts
- Designing a noise-immune layout on a prototype PCB and packaging the final unit inside a standard DIN rail enclosure for field deployment
Kit Contents
| Component | Quantity |
|---|---|
| Arduino Mega 2560 | 1 |
| NCN5121 KNX Transceiver | 1 |
| LM2596 Buck Converter | 1 |
| 0.96in OLED | 1 |
| 100nF Caps | 15 |
| 4.7k? Resistors | 5 |
| 10k? Resistors | 5 |
| PCB Prototype Board | 3 |
| Enclosure DIN Rail | 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
This kit is meant for B.Tech EEE/ECE students tackling a Smart City or building automation capstone project, professional system integrators who maintain multi-story KNX installations for hotel chains or IT parks, and faculty setting up an ATL-grade lab with real industrial protocols. If you need to show a working KNX-to-MQTT bridge at a Smart India Hackathon or integrate legacy HVAC controllers into a new BMS dashboard, this kit delivers the exact hardware.
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?
Scan the QR code on the box to launch the AI companion that walks you through common wiring mistakes, KNX bus termination checks, and MQTT configuration. You can also reach us on WhatsApp for a direct text consultation.
Do I need an existing KNX bus or power supply to test the gateway?
The kit includes an LM2596 buck converter that can accept a standard 24-30V DC supply, but you will need a live KNX bus segment (or a KNX power supply) to see real telegrams. The AI guide shows how to simulate bus traffic using the companion sketch if a real bus is unavailable.
Can this gateway publish data to cloud MQTT brokers like AWS IoT or ThingsBoard?
Yes. The Arduino Mega uses an Ethernet or Wi-Fi shield (not included) to connect to any MQTT broker. The companion guide includes tested code for publishing to a local Mosquitto broker, and the same client works with cloud brokers after adjusting the server address and port.
Is soldering experience mandatory for this kit?
The kit includes a soldering iron and three prototype boards, so you will be soldering the NCN5121 breakout, OLED, and passive components onto the board. If you are new to soldering, the AI companion includes a short video-based tutorial to get you comfortable with the iron.
Arduino Mega + NCN5121 KNX transceiver bridges KNX bus telegrams to MQTT for legacy building automation integration.
What's in this kit
- Arduino Mega 2560
- NCN5121 KNX Transceiver
- LM2596 Buck Converter
- 0.96in OLED
- 100nF Caps x15
- 4.7k? Resistors x5
- 10k? Resistors x5
- PCB Prototype Board x3
- Enclosure DIN Rail
- 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