Temperature to RGB light?

Third party integrations
1

In the process of learning Home Assistant.
I would like to set a color of an RGB light based on a temperature sensor.
For now, just trying to control the amount of red.

In configuration.yaml I’ve added:

sensor:
  - platform: template
    sensors:
      rgb_color:
        friendly_name: "rgb_color"
        unit_of_measurement: "RGB"
        value_template: "[{{ states('sensor.lumi_lumi_weather_temperature') | float * 2}}, 20, 20]"

Then, in an automation I have:

alias: Test Set Color
description: ''
trigger:
  - platform: state
    entity_id: sensor.lumi_lumi_weather_temperature
condition: []
action:
  - service: light.turn_on
    target:
      device_id: xxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
    data:
      rgb_color: sensor.rgb_color
mode: single

In automation debug, I get an error
“None for dictionary value @ data[‘rgb_color’]”

How can I properly format the RGB output so that it is a [R,G,B] array and not a string?

2

You would need to template the rgb_color to the entity, but I have a feeling it will fail.

    data:
      rgb_color: "{{ states('sensor.rgb_color') }}"

You could try putting the template from your sensor into the automation. The following topic has a couple examples.

3

Using the HSB (hue/saturation/brightness) colour space makes it easy to map a temperature range to a hue, keeping the saturation and brightness constant. e.g. starting at a hue of 180° on the wheel and heading up to 360° with an equation if you don’t mind cyan = cold, red = hot and blue/purple representing a middle temperature.

Or going the other way round the hue wheel, blue, cyan, green, yellow, orange, red (cold → hot), which I find better.

e.g. this maps 16°C → 24°C to blue, cyan, green, yellow, orange, red and clamps temperatures below and above that range to blue or red respectively. Purple = faulty sensor.

  action:
    service: light.turn_on
    target:
      entity_id: light.your_light
    data:
      brightness: 255
      hs_color: >
        {% set temp = states('sensor.your_temp_sensor')|float(default=1001) %}
        {% if temp < 1000 %}
          {% set h = -30 * temp + 720 %}
          {% set hlim = ([0,h,240]|sort)[1]|int %}
          [ {{ hlim }}, 100 ]
        {% else %}
          [ 300, 100 ]
        {% endif %}

Untitled
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3 Likes
4

Thank you for the suggestion. It worked very well.
I’ve tweaked the code a bit, so it is easier to adjust the temperature limits and the hue limits:

action:
  - service: light.turn_on
    target:
      device_id: b6201bbcb55a701236b11c9515823c99
    data:
      brightness: 255
      hs_color: >
        {% set t_min = 60 %} 

        {% set t_max = 90 %} 

        {% set h_min = 240 %} 

        {% set h_max = 0 %} {% set t_input = states('sensor.lumi_lumi_weather_temperature')|float %} 

        {% set h_out = (h_max - h_min) / (t_max - t_min) * (t_input - t_min) + h_min %} 

        [ {{ ([0,h_out,240]|sort)[1]|int }}, 100 ] #limit output to 0 <= h_out <= 240
1 Like
5

You should provide a default for your |float filter. Mine defaults to over 1000°C so I can detect that and display a “fault” colour (purple, H: 300).

6

Hello,

I attempted to write a script using your example but it keeps on throwing error messages when loading the YAML configuration. I made the following script in the scripts.yaml file that i call using an automation (which is triggered by a temperature change of mytempsensor). I use a paulmann bulb: Paulmann 291.52 control via MQTT | Zigbee2MQTT which specifies (as far as i can tell) using “color” and then specifying hue and saturation instead of “color_hs”.

temp_to_hue:
    alias: "Adjust Light Based on Temperature"
    trigger:
    - platform: state
      entity_id: sensor.mytempsensor
    condition: []
    action:
    - service: light.turn_on
      target:
        entity_id: light.mylight
      data:
        brightness: 254
        color: >
            {% set temp = states('sensor.mytempsensor') | float(default=1000) %}
            {% if temp < 1000 %}
            {% set h = -30 * temp + 720 %}
            {% set hlim = ([0,h,240]|sort)[1]|int %}
            ["hue":"{{ hlim }}","saturation":"100"]
            {% else %}
            ["hue":"300","saturation":"100"]
            {% endif %}
        mode: single

I notice there is a trigger in the script as well, is that necessary as i already use the same trigger (temp change) in the automation?

Many thanks!

7

That is not a valid script. Scripts do not have trigger or conditions or actions blocks. Only a sequence block.

8

Thanks! Managed to get it working now.