Intellihome
Home Assistant Connect ZBT-2
What it is: A USB adapter from Nabu Casa for Home Assistant. It runs either as a Zigbee coordinator or as a Thread radio, not both at once. For Zigbee it works with ZHA and Zigbee2MQTT. Successor to the discontinued ZBT-1 (formerly SkyConnect). ZBT-2 docs
The recommended option for customers is an SLZB network coordinator, see Home Assistant Connect SLZB. This page remains as a reference for the Nabu Casa USB adapter.
Specifications
- SoC: Silicon Labs MG24. USB-serial bridge: ESP32-S3. ZBT-2 docs
- Protocols: Zigbee 3.0 or Thread, only one at a time. No Bluetooth or Z-Wave. ZBT-2 docs
- Hardware and software are open source; the enclosure opens without glue or clips. ZBT-2 docs
- Power and data: USB-C, 5 V DC, 500 mA. A USB-C → USB-A cable is included. ZBT-2 draft
- Radio: 2400–2483.5 MHz, 4.16 dBi antenna, omnidirectional, Ø 34 mm × 164 mm. ZBT-2 draft
- Dimensions: 125 × 125 × 315 mm, 350 g, polycarbonate. Indoor only, 0–65 °C. ZBT-2 draft
- According to the vendor 4× faster than the ZBT-1. ZBT-2 draft Synthesis: this matches the 460800 baud rate vs. 115200 on the ZBT-1 (see the table below).
Installation and placement
- Prerequisites: HA OS with the latest updates (Green, Yellow, Raspberry Pi), the included USB extension cable. With HA Container the adapter must be mapped into the container. ZBT-2 docs The hub needs a USB 2.0 port. ZBT-2 draft
- HA 2025.11+: from this version HA reliably discovers the adapter and offers firmware updates. ZBT-2 docs
- When adding it in HA, pick "Use as Zigbee adapter" and then Recommended (ZHA) or Custom (your own controller, e.g. Z2M). ZBT-2 docs
- Antenna vertical, screw it on gently; overtightening damages the adapter beyond repair. Not sideways on a wall. Don't remove the foam inside the antenna; it keeps the antenna stable and removing it doesn't improve performance. ZBT-2 docs
- Fix it permanently only after checking nothing interferes at that spot. Interference sources: see Zigbee. ZBT-2 docs
Zigbee2MQTT
ZHA is the officially supported option; Z2M has official compatibility with Silicon Labs radios running EmberZNet firmware. ZBT-2 docs Z2M configuration:
serial:
adapter: ember
port: /dev/serial/by-id/usb-Nabu_Casa_ZBT-2_<usb-serial-number>-if00-port0
baudrate: 460800
rtscts: true
ZHA is active in HA by default. When using Z2M, delete and ignore the discovered ZHA integration, otherwise they will fight over the adapter. ZBT-2 docs
Status LED
| Pattern | State |
|---|---|
| off | normal operation, joined to a Zigbee or Thread network (or powered off) |
| pulsing | connecting to a network |
| fast blinking | wrong antenna orientation, remount vertically (initial setup only) |
| orange 4× → red → pulsing blue | progress of a button reset |
Source: ZBT-2 docs.
Firmware
Zigbee (EmberZNet / EZSP) is preinstalled. Thread (OpenThread RCP) turns it into a border router with the OTBR app. Install and update from the ZBT-2 integration page in HA, natively with a notification since HA 2025.11. ZBT-2 docs
For advanced users universal-silabs-flasher; firmware recovery via the Open Home Foundation Toolbox (web, Chrome). ZBT-2 docs
Repeater (router) firmware, experimental: the ZBT-2 as a standalone Zigbee router powered by a USB charger (5 V, ≥1 A). Works with any coordinator. Don't use it on your coordinator; going back requires reflashing via the Toolbox. ZBT-2 docs
Data, reset and handing over
- In Zigbee mode it stores network information including the private network key. In Thread mode nothing, HA holds the data. ZBT-2 docs
- The coordinator settings are part of HA backups (when ZHA starts and then every 24 h). ZBT-2 draft See Zigbee.
- Removing the integration does not reset the adapter. ZBT-2 draft
- Button reset: delete the integration (migrate the network first if needed), then press and hold the button with a pin. It wipes the entire NVRAM including the network key; afterwards the adapter is safe to pass on. In Thread mode the reset has no effect. ZBT-2 docs
Contradiction
ZBT-2 draft (pre-release 2025) said a reset only happens automatically during migration and a "few clicks" reset would come later. ZBT-2 docs (2026) describes a button reset. The official documentation applies.
Gotchas
- Two ZBT-2s with ZHA at once are not possible; ZHA is single instance. Another adapter with deCONZ or Z2M alongside a ZBT-2 with ZHA is fine. ZBT-2 docs
- After migration the ZBT-2 takes over the old adapter's IEEE address, so don't use the old adapter with the same HA anymore. ZBT-2 docs Migration procedure: Zigbee coordinator migration.
- ZHA does not support Zigbee Green Power (ZGP). ZBT-2 docs
- Without routers the coordinator handles at most 32 end devices, see Zigbee. ZBT-2 docs
Related
Sources
- ZBT-2 docs: official documentation (primary).
- ZBT-2 draft: pre-release draft (superseded). Used only for specifications the official docs don't state in text.