Atag One Homebridge plugin

This plugin adds HomeKit support for the Atag One Thermostat. This plugin requires no credentials for communicating with the thermostat, because it communicates locally to the thermostat.

Example config.json

{
  "accessory": "AtagOne",
  "name": "Atag One"
}

Optionally you can pass a minimumTargetValue key to the JSON to specify the lowest target temperature in HomeKit (the default is 16 degrees celsius).

In addition, you can specify an ipAddress key to specify the ip-address of the thermostat in case it can't be found in the network.

Extra, you can specify a cacheUrl option, to enable or disable storing the base url of your Atag One. This storing is used to speed up the booting of this plug-in. Without storing the base url, you have to wait for a broadcast message from the Atag One to control the Atag One.

Device discovery

To discover the thermostat in the local network, we can use the fact that the thermostat broadcasts a message approximately once every 10 seconds to the local network that it’s connected to. If you set up a listener for this message, you can access the IP-address of the device that sent the message. In our case this is the thermostat.

As long as Homebridge is running, this plugin will listen for this message. So, if the IP-address of the thermostat changes, this plugin detects it right away and will automatically use the newly found IP-address for communication.

An example config.json with these two keys:

{
  "accessory": "AtagOne",
  "name": "Atag One",
  "minimumTargetValue": 10,
  "ipAddress": "10.0.0.19",
  "cacheUrl": true
}