# MQTT API
The device is capable to register to a MQTT broker to publish data and subscribe to specific topics.

The MQTT service has to be enabled and configured properly in the device configuration via web interface (`Settings` -> `Configuration` -> section `MQTT`)

The following parameters have to be defined:
* URI
* MainTopic (optional, if not set, the hostname is used)
* ClientID (optional, if not set, `AIOTED-` + the MAC address gets used to make sure the ID is unique)
* User (optional)
* Password (optional)
* RetainFlag (optional)

## Published topics

### Status
`MainTopic`/{status topic}, e.g. `watermeter/status`

* #### Connection

* #### Interval

* #### MAC

* #### IP

* #### Hostname

* #### Uptime

* #### FreeMem

* #### WifiRSSI

* #### CPUTemp

* #### Status

### Result
`MainTopic`/{NumberName}/{result topic}, e.g. `watermeter/main/value`

* #### Value

* #### Raw

* #### Error

* #### JSON

* #### Rate

* #### Rate_per_time_unit
  The time Unit gets set with the Home Assistant Discovery, e.g. `h` or `m` (minutes)

* #### Rate_per_digitalization_round
  The `interval` defines when the next round gets triggered

* #### Changeabsolut

* #### Timestamp

* #### JSON
  All relevant results in JSON syntax

### GPIO
`MainTopic`/{GPIO topic}, e.g. `watermeter/GPIO/GPIO12`

* #### GPIO/GPIO{PinNumber}
  Depending on device configuration (`Settings` --> `Configuration` --> Chapter `GPIO`)


## Subscibed topics
`MainTopic`/{subscribed topic}, e.g. `watermeter/ctrl/flow_start`

### Control

* #### ctrl/flow_start
  Trigger a flow start by publishing to this topic (any character, length > 0)

* #### GPIO/GPIO{PinNumber}
  Depending on device configuration (`Settings` --> `Configuration` --> Chapter `GPIO`)