Today's quest I receive temperature values. 30 - 75 (example) I want to display that with a RGB LED. Say 30 - 36 --> blue. Green starts to creep in then. 36 - 40 --> Blue fades out and becomes green. Towards the 40, red starts to come in. 40 - 75 --> Green fades out and it becomes only red. …

Here is an adaption of that code. As you didnt specify how you want RGB to be represented, I just spit out a whole bunch of different values (r,g,b,val,hex) in the payload object. Ignore the pink image nodes at the bottom - they are to demonstrate it working. [Oyu8DFZp4Z] [{"id":"e17b05ed.383be…

[image] Trying_to_learn: map 1 - 32 against 0 - 256 The Range node will do that. Possibly use three, one for each colour, with appropriate input ranges.

Thanks Colin. What is now biting me is that it isn't that simple. :frowning: (When is it?) Did you look at the flow? I kind of cheated with the blue in that it was reversed with the value. eg: So: blue 0 - 5 would give an output from 255 - 0 (Darkening as the value went up) red was simpl…

If you want one of them to go up then down again then for that colour you could use a Switch node to split the input above or below 52 to two outputs. Then use a Range node in each output configured to convert the ranges 40:52 to 0:255 and 52:64 to 255:0, or whatever the numbers are. Make sure you…

This is the flow as I have it. Input is the left most link node. output is right most link node. It uses flow context to store the RGB values. External nodes needed: node-red-contrib-fan node-red-contrib-simple-gate The other two link nodes with no names are used to control the gate node and …

What has all that got to do with the question here, which is how to map an input value of 30 to 75 to give you RGB values? All you need to test that is a slider (or inject nodes) and the logic to generate the colours.

Sorry, was that to me or Steve? The reply is to me, so I am not sure.

It is to you, you posted a flow with an explanation of what it does, including using non-core nodes, but that doesn't seem to have anything to do with question you asked, which is how to map a number to RGB values.

I use non-core nodes because a: the allow me to isolate the real data from fake data I am injecting. and b) I like the fan node as it allows me to sectionalise parts of the code and allow me to move blocks easily. I know the newer version allows something like that, but it is annoying if/when I hav…

[image] Trying_to_learn: We seem to be having a bit of misunderstanding. Yes we do. The title of this thread is Colour mapping - help needed to create RGB value. In the first post you said you had a value in the range 30-75 and you want to map that to RGB values. The fan node and those befo…

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"Colour mapping" - help needed to create RGB value

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Steve-Mcl 26 September 2020 08:05 6

Andrew, have a look at this post. In the colourise function is some code you can adapt to generate a heat colour.

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"Colour mapping" - help needed to create RGB value

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