TUL TUL

TPUART KNX/EIB interface over USB or Wi-Fi (ESP32-C6 + NCN5130), usable as a standalone Wi-Fi-to-KNX coupler.

TPUART KNX interface (ESP32-C6)

TUL V3.5: USB-C socket, ESP32-C6 module, NCN5130 transceiver and the WAGO push-in terminals for the bus

General

This module gives a host access to the KNX bus — as a serial interface over USB, or over Wi-Fi and Bluetooth instead. It replaces the old ATmega-based TUL stick.

What ships today is the ESP32-C6 version. Against the earlier ESP32-C3 it adds Wi-Fi 6 and, more to the point, an IEEE 802.15.4 radio — the one that makes Thread and Zigbee, and with them Matter over Thread, possible on this stick at all.

The ESP32-C6-MINI-1 module on the board, next to the KNX terminals

Specs

isolated KNX bus access through an onsemi NCN5130 transceiver
ESP32-C6: Wi-Fi 6 (802.11ax, 2.4 GHz), Bluetooth 5 LE, IEEE 802.15.4 (Thread, Zigbee)
board revision V3.5
status LEDs
USB-C socket
on-board Wi-Fi chip antenna
WAGO push-in terminals for the bus
plastic enclosure, USB cable and an Ethernet or Ethernet-with-PoE extension are options in the shop

Firmware

Every variant is flashed from the browser — no toolchain, no installation. The installer detects whether it is talking to a C3 or a C6 and writes the matching build. (Variants and chips below are what the live installer manifests listed on 2026-08-29.)

KNX/IP tunnel — the straightforward one

A UDP tunnel device, which is what Home Assistant and the usual tools expect. Thanks to the OpenKNX stack no separate knxd installation is needed. Runs on C3 and C6.

Installer: install.busware.de/ip4knx/ → KNX/IP for TUL
Source: github.com/tostmann/ip4knx

KNX-TP ↔ TCP bridge (cdc2net)

The transparent bridge: raw TP-UART over TCP, with no USB host involved. Wi-Fi is set up right after flashing over Improv. Runs on C3 and C6.

Installer: install.busware.de/cdc2net/tul/
Reachable on TCP port 2329 — knxd -b tpuarttcp:<ip>:2329
Source: github.com/tostmann/cdc2net

USB serial emulation

The raw path, for your own software. Runs on C3 and C6.

Installer: install.busware.de/TUL → USB-serial emulation
The TPUART appears as /dev/ttyACMx, so with knxd: ... -b tpuarts:/dev/ttyACM0
Example code: serial transparent example

KNX commissioning over MCP

Turns the TUL into a KNX interface an agent can commission through, not just talk across: it assigns individual addresses, reads and writes device memory and properties, drives the load state machines and installs address and association tables — the connection-oriented management services ETS itself uses — and publishes to MQTT with Home Assistant discovery. The stick answers MCP on your LAN directly.

Installer: install.busware.de/TUL/mcp/
What it does in detail: BREMA for KNX
Documentation and the worked commissioning session: github.com/tostmann/BREMA

MQTT and Matter for TUL

MQTT for TUL and Matter for TUL are offered in the installer as well, but their manifests currently carry an ESP32-C3 build only — so they do not apply to a C6 stick as it ships today.