MQTT JSON Light

The mqtt_json light platform lets you control a MQTT-enabled light that can receive JSON messages.

This platform supports on/off, brightness, RGB colors, XY colors, color temperature, transitions, short/long flashing and white values. The messages sent to/from the lights look similar to this, omitting fields when they aren’t needed:

{
  "brightness": 255,
  "color_temp": 155,
  "color": {
    "r": 255,
    "g": 255,
    "b": 255,
    "x": 0.123,
    "y": 0.123
  },
  "effect": "colorloop",
  "state": "ON",
  "transition": 2,
  "white_value": 150
}

In an ideal scenario, the MQTT device will have a state topic to publish state changes. If these messages are published with the RETAIN flag, the MQTT light will receive an instant state update after subscription and will start with the correct state. Otherwise, the initial state of the light will be off.

When a state topic is not available, the light will work in optimistic mode. In this mode, the light will immediately change state after every command. Otherwise, the light will wait for state confirmation from the device (message from state_topic).

Optimistic mode can be forced, even if state topic is available. Try enabling it if the light is operating incorrectly.

# Example configuration.yaml entry
light:
  - platform: mqtt_json
    command_topic: "home/rgb1/set"

Make sure that your topics match exact. some-topic/ and some-topic are different topics.

XY and RGB can not be used at the same time. If both are provided, XY overrides RGB.

Comparison of light MQTT platforms

Examples

In this section you find some real life examples of how to use this sensor.

Brightness and RGB support

To enable a light with brightness and RGB support in your installation, add the following to your configuration.yaml file:

# Example configuration.yaml entry
light:
  - platform: mqtt_json
    name: mqtt_json_light_1
    state_topic: "home/rgb1"
    command_topic: "home/rgb1/set"
    brightness: true
    rgb: true

Brightness and no RGB support

To enable a light with brightness (but no color support) in your installation, add the following to your configuration.yaml file:

# Example configuration.yaml entry
light:
  - platform: mqtt_json
    name: mqtt_json_light_1
    state_topic: "home/rgb1"
    command_topic: "home/rgb1/set"
    brightness: true

Brightness Scaled

To enable a light using a brightness scale other than 8bit the brightness_scale option may be added to denote the “fully on” value:

# Example configuration.yaml entry
light:
  - platform: mqtt_json
    name: mqtt_json_light_1
    state_topic: "home/light"
    command_topic: "home/light/set"
    brightness: true
    brightness_scale: 4095

Home Assistant will then convert its 8bit value in the message to and from the device:

{
  "brightness": 4095,
  "state": "ON",
}

Implementations

• A full example of custom lighting using this platform and an ESP8266 microcontroller can be found here. It supports on/off, brightness, transitions, RGB colors, and flashing.

• There is also another implementation forked from the above repo, it supports all the same features but is made for addressable LED strips using FastLED on a NodeMCU V3 it can be found here.

• MQTT JSON Light is another implementation for ESP8266 including MQTT discovery.

• esphomelib is a library for ESP32-based boards that has many of Home Assistant’s MQTT features (like discovery) pre-implemented and provides high-level abstractions for components such as lights or sensors.