BLU devices in Home Assistant

Why they are not Shelly devices

A BLU H&T does not appear under the Shelly integration, and people reasonably conclude something is broken. Nothing is.

BLU devices speak Bluetooth, not Wi-Fi. They have no IP address, they are not on the network, and the Shelly integration — which talks to devices over the network — has nothing to talk to.

What they do instead is broadcast. Every so often a BLU sensor shouts its readings into the air in a format called BTHome, an open standard rather than a Shelly one. Home Assistant has a BTHome integration that listens for exactly that.

The one exception is BLU TRV, which the Shelly integration does support, through a Shelly BLU Gateway Gen3.

Something has to hear them

Home Assistant needs a Bluetooth receiver within range of the sensor. Three ways, in increasing usefulness:

A Bluetooth adapter on the Home Assistant machine. Works, and covers one room. A Raspberry Pi in a cupboard will not hear a sensor two floors up.

A Shelly device as a gateway. Almost any mains-powered Shelly — Plus, Pro, Gen3 or Gen4 — can relay Bluetooth advertisements onto the network. Enable Bluetooth gateway in the device’s settings, and it starts forwarding what it hears.

This is the one that makes the whole thing practical. A relay already fitted behind a light switch becomes a Bluetooth receiver for that part of the house, at no extra cost and with no extra hardware.

Several gateways. Enable it on devices spread through the building and the coverage follows the installation. A sensor heard by two gateways is not a problem — Home Assistant takes whichever signal is stronger.

Battery-powered Shelly devices cannot act as gateways. They are asleep most of the time, which is the whole point of them.

Adding a BLU sensor

With a receiver in place, most of this happens by itself.

1. Power the sensor and make sure it is within range of a gateway or adapter
2. Home Assistant discovers it under Settings → Devices & services, as a BTHome device
3. Press Configure and confirm
4. Assign it to an area and name the entities

If nothing appears, press the sensor’s button to make it transmit. A door sensor that has not been opened for a week has not said anything for a week.

Encrypted sensors

BLU devices can broadcast encrypted, and several do by default. Home Assistant then sees the device but cannot read it, and asks for a bind key.

Get the key from the Shelly BLE Debug app: open the device, and the encryption key is in its settings. Paste it into Home Assistant when prompted, and the readings appear.

This is worth knowing before you conclude a sensor is faulty. An encrypted sensor that Home Assistant cannot decode looks exactly like a sensor that is not reporting.

Tips & best practices

• Enable the gateway on a device that is central, not convenient. Bluetooth range is short and walls are unkind to it.
• Check the battery entity. BTHome exposes it, and a BLU sensor that has gone quiet is far more often flat than faulty.
• Note that reporting is not continuous. BLU sensors transmit on a change or on an interval, so a temperature that updates every few minutes is behaving normally.
• The same sensor can serve both systems. A BLU device reporting into Home Assistant still works in the Shelly app, and can still be paired directly to a relay — see dimming with BLU Wall Switch.
• A Shelly gateway is not a Bluetooth hub. It forwards what it hears; it does not extend range or improve a weak signal.

Video tutorial

Adding BLU devices to Home Assistant, including the gateway setup.

Loads YouTube when you press play. Watch on YouTube

By ShellyGuide on YouTube

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