MQTT Topics¶

geiger2mqtt publishes one state topic for the radiation readings plus the framework's availability, heartbeat and error topics. All topics start with GEIGER2MQTT_MQTT__TOPIC_PREFIX (default geiger2mqtt).

geiger2mqtt subscribes to no topics.

Radiation state¶

Topic: geiger2mqtt/radiation/state

Published every PUBLISH_INTERVAL seconds (default 30), even when the values have not changed. The first message comes 60 seconds after the start.

{ "cpm": 21, "dose_rate": 0.1197, "dose_rate_avg": 0.1123 }

Availability¶

Topic: geiger2mqtt/radiation/availability

"online" while readings are published. When no pulse has arrived for NO_PULSE_TIMEOUT seconds (default 300), geiger2mqtt publishes "offline", stops publishing state and reports NoPulseError on the error topics. The next pulse brings the sensor back "online" with the next reading; the app keeps running throughout. NO_PULSE_TIMEOUT=0 disables the check.

Status heartbeat¶

Topic: geiger2mqtt/status

A retained JSON heartbeat with the app version, uptime and the status of the radiation entity. On disconnect, the broker publishes the last will "offline".

Errors¶

Topics: geiger2mqtt/error and geiger2mqtt/radiation/error

Not retained. The payload carries error_type, message, device and timestamp. Messages are reduced to the exception class name unless GEIGER2MQTT_MQTT__ERROR_PUBLISH_VERBOSE=true. A persisting error is republished as a reminder (2^nd, 4^th, 8^th, ... failure in the first hour, then hourly).

Home Assistant discovery¶

On the first connection, geiger2mqtt publishes retained discovery configs under homeassistant/sensor/geiger2mqtt/<object_id>/config. All three sensors read geiger2mqtt/radiation/state and share the radiation availability topic.

Home Assistant has no device class for radiation, so the sensors carry none.