I obtained a Plasma 2350 W.
I located some firmware that allowed me to get an RBG (no W) test program working:
plasma_2350_w-v1.0.0-micropython-with-filesystem
I don’t know enough to know how to determine if the firmware supports the W led.
I really need to control the W led (more than the RGB ones) so any help would be most welcome and greatly appreciated.
Thanks.
Frederick
The docs are here: plasma/docs/plasma.md at main · pimoroni/plasma · GitHub
The link above is a direct link to the section that deals with RGBW strips.
Hello,
Thank you for the link.
I read through the information there but see no example of how to set the W led, only the RGB ones.
The RGB ones are working fine.
Maybe I’m just not understanding what they are showing.
Frederick
The link is to this section:
The section explicitly is about WS2812-RGBW LEDs. And there is even a code example on how to to it.
But in fact they miss an example on how to pass the w part. You can just add it as an additional parameter to set_rgb().
That does indeed work.
Interesting that the example didn’t cover that 4th parameter.
Thanks very much.
Frederick
There is even a fifth parameter (gamma=True). So there is some automatic gamma-correction done.
Ah, I see you have now switched to a Plasma 2350 W from the Yukon you were originally trying with. Well I hope my answer in your other thread is useful regardless.
Yes it was. I appreciate your taking the time to reply.
The Yukon is better suited to the project I have in mind but the Plasma gave me a chance to see how the RGBW strips would look.
Having seen the appearance of the White LEDs, I’m now thinking RGB strips will work fine as the “white” the create is sort of a blueish-white which actually looks very good for my needs.
Frederick
Gamma correction? How does that work?
Thanks.
Frederick
Gamma correction works by multiplying color-values with a correction factor so the brightness that the human eye perceives matches better. E.g.: the brightness difference between 10% and 20% is perceived as much higher than the difference between 40% and 50%. So you scale behind the scenes to make both differences similar. It is called gamma-correction, because the mathematical curve has a parameter called gamma that describes the curve.
And this correction can be done without any knowledge of the characteristics of the LED strip?
Good stuff.
Frederick
No, of course not. But it is a good approximation. If you want to do better, you have to do it yourself. You will find sophisticated gamma-correction libraries, but I doubt it is really worth the effort.
I do appreciate the information. I love to learn.
Frederick
I’ve added a note to the Plasma docs about how to invoke the mysterious W parameter :)
