EUL EUL

EUL32: EnOcean interface for USB and Wi-Fi (TCM 515 + ESP32-C6), Ethernet via expansion board — freely programmable, more than a serial-to-USB bridge.

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EUL32 — EnOcean interface for USB and Wi-Fi

EUL32, board revision V3.4: antenna socket, EnOcean TCM 515, ESP32-C6-MINI-1 module and USB-C receptacle, from left to right

General

The EUL32 connects EnOcean radio in the 868 MHz band to a computer via USB, or to an IP network via Wi-Fi; Ethernet is available through an expansion board. An EnOcean TCM 515 does the radio, an ESP32-C6 sits between it and the host — so this is not just a serial-USB bridge like many other EnOcean USB devices: what it does is decided by the firmware you install.

It ships without firmware, and as delivered it does not transmit — without firmware the TCM 515 is held in reset. It is a bare circuit board without enclosure, meant for DIY use, and comes without an antenna (see below). It replaces the old TCM310-based stick.

The EUL32 at an angle: the TCM 515 next to the antenna socket, the ESP32-C6-MINI-1 module next to the USB-C receptacle

Specs

From the datasheet (Rev. 1.2):

EnOcean TCM 515: 868.300 MHz, ASK, 125 kbit/s, ESP3 interface; transmit power at most +10.8 dBm, duty cycle ≤ 1 % enforced by the module in hardware
RP-SMA socket for an external 868 MHz antenna (not supplied)
Espressif ESP32-C6-MINI-1-H4: Wi-Fi 6 (802.11b/g/n/ax, 2.4 GHz), Bluetooth LE 5.3, IEEE 802.15.4; 4 MB flash; PCB antenna in the module
USB-C: power, serial port and firmware installation over one cable
expansion connector J2 (14-pin FPC: SPI, GPIO, power), e.g. for the W5500EXT Ethernet expansion
blue LED (firmware-controlled), push button “BOOTLOAD”
board revision V3.4, bare board (IP00), 54.0 × 19.0 × 7 mm, 7 g; dry indoor locations, 0 … +40 °C
plastic enclosure, USB cable and an Ethernet or Ethernet-with-PoE extension are options in the shop

Antenna

The antenna socket is RP-SMA (reverse polarity) — a plain SMA antenna does not fit. For EnOcean use only an antenna that is passive, approx. 50 Ω, made for 868 MHz, with a gain of at most 0 dBd (VSWR ≤ 3:1 recommended). An antenna with higher gain is not covered by the radio approval of the TCM 515. Without an antenna there is no EnOcean reception.

Documents

Datasheet and operating instructions for the EUL32 (article no. EUL32-OEM, board revision V3.4), Rev. 1.2 of 2026-09-26:

Datasheet: English (PDF) · German (PDF)
Operating instructions: English (PDF) · German (PDF)

Further references:

TCM 515 transceiver

Firmware

Every variant is flashed from the browser (Chrome, Edge or Opera — they support Web Serial) at the EUL firmware installer — no toolchain, no installation. (The two variants below are what the live installer manifest listed on 2026-09-25; both run on C3 and C6.)

USB-serial emulation

The transparent path: the TCM 515 appears on the host as a serial port (/dev/ttyACMx), speaking ESP3. With “USB-serial emulation” the TCM 515 transmits only when the software on the computer tells it to, and Wi-Fi stays off.

Installer: install.busware.de/EUL → USB-serial emulation
In FHEM: define ENO2 TCM ESP3 /dev/ttyACM0
Example code: serial transparent example

EnOcean ↔ TCP bridge (cdc2net)

The TCM 515 on the network, over Wi-Fi or Ethernet: a byte-transparent raw-TCP pipe, so the ESP3 decoding stays on the host. Wi-Fi is set up right after flashing over Improv.

Installer: install.busware.de/EUL → EnOcean ↔ TCP Bridge (cdc2net)
Reachable on TCP port 2329 (configurable in the web UI) — in FHEM: define ENO2 TCM ESP3 <ip>:2329
Source: github.com/tostmann/cdc2net

Home Assistant

We recommend the enoceanmqtt-addon.

Availability

This unit is available in our shop.