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Networking and MQTT

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Roman Kuraev edited this page Jul 10, 2026 · 1 revision

Networking and MQTT

Wi-Fi modes

Rewair operates in exactly one Wi-Fi role at a time:

  • Station mode joins a saved home network.
  • Setup mode hosts an access point for configuration.

With no stored network, the device boots directly into the open rewair-setup-<xxxx> access point on channel 6 at 192.168.0.1/24. The suffix is the final two bytes of the Wi-Fi MAC address. WICED supplies DHCP, DNS redirection, and captive-portal redirects.

When saved networks exist, boot-time autojoin is attempted three times before falling back to the setup AP. A station link loss after a successful join does not enter setup mode; Rewair continues retrying the saved networks.

Submitting /api/join in setup mode stores the chosen credentials using the scan cache, completes the HTTP response, and switches to station mode on the network thread. /api/reset clears Wi-Fi, settings, and MQTT configuration and reboots into setup mode.

The fallback AP retries saved networks about every five minutes. It delays a retry while a client is associated, preventing an active setup session from being interrupted.

MQTT and Home Assistant

In the device portal, open Settings → MQTT & Home Assistant → Configure. Enter the hostname or IP address and port of the broker used by Home Assistant. Username/password authentication is optional.

Rewair currently supports MQTT 3.1.1 over unencrypted TCP, normally port 1883. Use it only on a trusted local network; MQTT over TLS is not included.

Home Assistant discovery is enabled by default. Rewair creates seven entities:

  • temperature
  • humidity
  • carbon dioxide
  • VOC
  • dust
  • illuminance
  • air-quality score

The device identifier is derived from the Wi-Fi MAC and remains stable across renames and reboots.

Retained telemetry is published to:

rewair/rewair_<12-hex-mac>/state

The adjacent availability topic carries retained online/offline state and is configured as the last will. The portal allows custom state-topic and Home Assistant discovery prefixes. Credentials and settings are stored in WICED DCT. Factory reset removes retained discovery records when the broker is reachable, then clears the local settings.

To inspect the broker:

mosquitto_sub -h <broker> -u <user> -P '<password>' -v \
  -t 'rewair/#' -t 'homeassistant/sensor/#'

Rewair

Technical notes

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