Homebridge Hue Temperature Delta

This is Homebridge plugin for calculating the delta between two Hue temperature sensors. It creates a new temperature device for each delta. My usage for this was to be able to display the temeperature difference between an interior and exterior sensor, but there could be other use cases.

It currently only supports sensors with type ZLLTemperature.

You'll need the following to add a delta device successfully

• The IP address of your Hue bridge.
• A username (token) on your Hue bridge.

You can follow the guide here for these.

Once you have these, you will need to find the MAC addresses of your Hue sensors. These can be found by querying your Bridge API.

curl http://$BRIDGE_IP/api/$USERNAME/sensors

You should note that Hue motion detectors (what I'm using) are technically 3 sensors, motion, light and temperature. They share the same MAC address which can be found in the first part of the uniqueid field of the sensor.

Setup Development Environment

To develop Homebridge plugins you must have Node.js 18 or later installed, and a modern code editor such as VS Code. This plugin template uses TypeScript to make development easier and comes with pre-configured settings for VS Code and ESLint. If you are using VS Code install these extensions:

• ESLint

Install Development Dependencies

Using a terminal, navigate to the project folder and run this command to install the development dependencies:

npm install

Update package.json

Open the package.json and change the following attributes:

• name - this should be prefixed with homebridge- or @username/homebridge-, is case-sensitive, and contains no spaces nor special characters apart from a dash -
• displayName - this is the "nice" name displayed in the Homebridge UI
• repository.url - Link to your GitHub repo
• bugs.url - Link to your GitHub repo issues page

When you are ready to publish the plugin you should set private to false, or remove the attribute entirely.

Update Plugin Defaults

Open the src/settings.ts file and change the default values:

• PLATFORM_NAME - Set this to be the name of your platform. This is the name of the platform that users will use to register the plugin in the Homebridge config.json.
• PLUGIN_NAME - Set this to be the same name you set in the package.json file.

Open the config.schema.json file and change the following attribute:

• pluginAlias - set this to match the PLATFORM_NAME you defined in the previous step.

Build Plugin

TypeScript needs to be compiled into JavaScript before it can run. The following command will compile the contents of your src directory and put the resulting code into the dist folder.

npm run build

Link To Homebridge

Run this command so your global installation of Homebridge can discover the plugin in your development environment:

npm link

You can now start Homebridge, use the -D flag, so you can see debug log messages in your plugin:

homebridge -D

Watch For Changes and Build Automatically

If you want to have your code compile automatically as you make changes, and restart Homebridge automatically between changes, you first need to add your plugin as a platform in ~/.homebridge/config.json:

{
...
    "platforms": [
        {
            "name": "Config",
            "port": 8581,
            "platform": "config"
        },
        {
            "name": "<PLUGIN_NAME>",
            //... any other options, as listed in config.schema.json ...
            "platform": "<PLATFORM_NAME>"
        }
    ]
}

and then you can run:

npm run watch

This will launch an instance of Homebridge in debug mode which will restart every time you make a change to the source code. It will load the config stored in the default location under ~/.homebridge. You may need to stop other running instances of Homebridge while using this command to prevent conflicts. You can adjust the Homebridge startup command in the nodemon.json file.

Customise Plugin

You can now start customising the plugin template to suit your requirements.

• src/platform.ts - this is where your device setup and discovery should go.
• src/platformAccessory.ts - this is where your accessory control logic should go, you can rename or create multiple instances of this file for each accessory type you need to implement as part of your platform plugin. You can refer to the developer documentation to see what characteristics you need to implement for each service type.
• config.schema.json - update the config schema to match the config you expect from the user. See the Plugin Config Schema Documentation.

Versioning Your Plugin

Given a version number MAJOR.MINOR.PATCH, such as 1.4.3, increment the:

1. MAJOR version when you make breaking changes to your plugin,
2. MINOR version when you add functionality in a backwards compatible manner, and
3. PATCH version when you make backwards compatible bug fixes.

You can use the npm version command to help you with this:

# major update / breaking changes
npm version major

# minor update / new features
npm version update

# patch / bugfixes
npm version patch

Publish Package

When you are ready to publish your plugin to npm, make sure you have removed the private attribute from the package.json file then run:

npm publish

If you are publishing a scoped plugin, i.e. @username/homebridge-xxx you will need to add --access=public to command the first time you publish.

Publishing Beta Versions

You can publish beta versions of your plugin for other users to test before you release it to everyone.

# create a new pre-release version (eg. 2.1.0-beta.1)
npm version prepatch --preid beta

# publish to @beta
npm publish --tag=beta

Users can then install the beta version by appending @beta to the install command, for example:

sudo npm install -g homebridge-example-plugin@beta

Best Practices

Consider creating your plugin with the Homebridge Verified criteria in mind. This will help you to create a plugin that is easy to use and works well with Homebridge. You can then submit your plugin to the Homebridge Verified list for review. The most up-to-date criteria can be found here. For reference, the current criteria are:

• The plugin must successfully install.
• The plugin must implement the Homebridge Plugin Settings GUI.
• The plugin must not start unless it is configured.
• The plugin must not execute post-install scripts that modify the users' system in any way.
• The plugin must not contain any analytics or calls that enable you to track the user.
• The plugin must not throw unhandled exceptions, the plugin must catch and log its own errors.
• The plugin must be published to npm and the source code available on GitHub.
  • A GitHub release - with patch notes - should be created for every new version of your plugin.
• The plugin must run on all supported LTS versions of Node.js, at the time of writing this is Node.js v16 and v18.
• The plugin must not require the user to run Homebridge in a TTY or with non-standard startup parameters, even for initial configuration.
• If the plugin needs to write files to disk (cache, keys, etc.), it must store them inside the Homebridge storage directory.

Useful Links

Note these links are here for help but are not supported/verified by the Homebridge team

• Custom Characteristics