Accessor: devices/Lifx

This accessor discovers and controls a Lifx lightbulb.

If the bulbs are already set up (through the Lifx mobile app for example), then the host running this accessor needs to be connected to the same LAN.

Otherwise, with an unconfigured bulb, you can connect your computer to the Lifx network provided by the bulb (an open Wifi network with a name like "LIFX_Axx_xxxxxx").

If you have a bulb that has been configured to operate on some other network, you can reset it to factory defaults by turning it on and off five times in succession.

While it is possible to interact with Lifx bulbs over the Internet by sending HTTP requests to the Cloud, this module does not provide such mechanism.

The communication with Lifx light bulbs is done over UDP/IP. Messages are arrays of numeric bytes ordered in little-endian. The packets construction can be found in this link: https://lan.developer.lifx.com/docs/introduction

Upon initialization, this accessor creates a UDP socket for communication. There are two ways to configure this accessor in order to control a bulb:

• the first one consists on discovering Lifx bulbs on the network and then selecting the one to use.

• the second is by running a manual setup, where the light parameters are received in the input port. A use case of this scenario is when a server sends information about available devices and their parameters.

  Discovery starts if an input is provided in 'triggerDiscovery' input port. The accessor will broadcast discovery messages. Since available bulbs will be asynchronously sending State messages, the accessor will be listening. Discovery messages will be repeatedly sent every 'discoveryInterval' parameter value, if no device has been selected. Each newly discovered light bulb will be added to discoveredLifxLights array. Selecting a device
  is done by providing the index of the LifxLight in the array of discovered devices in the input port 'selectLight'.

  Once the light bulb is chosen and successfully configured, discovery will stop and the accessor will start to react to 'control' input.

  The control input is a JSON object that may have the following properties:

• on: 'on' to turn on; 'off' to turn off.
• hue: Color, for bulbs that support color. This is a number in the range 0-65535.

• color: Color, for bulbs that support color. This is a string that is converted into a hue number using the colorToHexHue variable.

  HSBK is used to represent the color and color temperature of a light. The color is represented as an HSB (Hue, Saturation, Brightness) value. Please refer to https://en.wikipedia.org/wiki/HSL_and_HSV A LifxLight is a class that has the following parameters:

• ipAddress: IP address of the bulb in the LAN.
• port: integer. It defaults to 56700 as noted in the Lifx developer API.
• macAddress: a string of 12 hex numbers (6bytes) that refer to the bulb macAddress.
• color: the current hue values.
• power: if true, then the bulb is switched on, false if switched off.

• userName: this is the name of the user. It can be used to filter the received messages.

  LifxLight class declares a set of functions for light control:

• swithOn(): switches the light on. The latest selected color is the one used.
• swithOff(): switches the light off.
• setColor(): changes the light color.

• probe(): sends a 'getState' message to ckeck if the light bulb is still working. This feature allows for fault-tolerance.

  The supported communication schemas between the accessor and the bulbs are the following:

  • To run discovery, a discovery message will be broadcasted. Bulbs will answer with a 'stateService' message.
  • To switch the light on or off, a 'setPower' message is sent. The bulb will answer with a 'statePower' message.
  • To set the light color, a 'setColor' message is sent. The bulb will answer with a 'stateLight' message.
  • To probe the light, a 'getLight' message is sent. The bulb will answer with a 'stateLight' message.