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From: Pavel Machek <pavel@ucw.cz>
To: Alexander Dahl <ada@thorsis.com>
Cc: linux-leds@vger.kernel.org, Luca Weiss <luca@z3ntu.xyz>
Subject: Re: Multicolor leds-gpio
Date: Thu, 6 Aug 2020 21:24:54 +0200	[thread overview]
Message-ID: <20200806192454.qasvwnqh33iavkf4@duo.ucw.cz> (raw)
In-Reply-To: <2050851.IQFrM7rjFq@ada>

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Hi!

> > > would it be possible to make the leds-gpio driver compatible with the new
> > > multicolor framework for a light that's composed of 3 leds (red, green,
> > > blue) and where each led is controlled via a gpio (so it can produce 8
> > > different colors)? As far as I can tell leds-gpio is too generic to
> > > support that but please correct me if I'm wrong. What's the way forward
> > > here for this use case? The same probably also applies to leds-pwm.
> > 
> > For pwm it definitely makes sense.
> 
> I think it also makes sense for plain GPIO, I asked the same thing last year 
> IIRC.

It may make sense, yes.

> > For gpio... well, I'm not sure you'll get useful colors that way. You
> > can probably still do multicolor, yes.
> 
> Let's assume a typical RGB LED, like the one on the SAMA5D27-SOM1-EK board, 
> you would roughly get those colors:
> 
> - R: red
> - G: green
> - B: blue
> - R + G: yellow
> - R + B: magenta
> - G + B: cyan
> - R + G + B: white
> 
> I count more than twice the colors as with the simple leds-gpio approach only. 
> ;-)

Well, you can still produce all the colors with three gpio leds.

And for resistors are not calibrated carefully, you'll get:

- R: red
- G: green
- B: blue
- R + G: green with hint of yellow
- R + B: blue
- G + B: blue
- R + G + B: blue

:-)

But yes, patch might be interesting. Will you create one?

Best regards,
									Pavel
-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html

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      reply	other threads:[~2020-08-06 19:25 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-08-05 21:56 Luca Weiss
2020-08-05 22:05 ` Pavel Machek
2020-08-06 10:52   ` Alexander Dahl
2020-08-06 19:24     ` Pavel Machek [this message]

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