Multicolor leds-gpio

Multicolor leds-gpio

[Luca Weiss]

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.
Regards
Luca

Re: Multicolor leds-gpio

[Pavel Machek]

[-- Attachment #1: Type: text/plain, Size: 778 bytes --]

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.

For gpio... well, I'm not sure you'll get useful colors that way. You
can probably still do multicolor, yes.

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

[-- Attachment #2: signature.asc --]
[-- Type: application/pgp-signature, Size: 195 bytes --]

Re: Multicolor leds-gpio

[Alexander Dahl]

Hei hei,

Am Donnerstag, 6. August 2020, 00:05:47 CEST schrieb Pavel Machek:
> > 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.

> 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. 
;-)

SCNR
Alex

Re: Multicolor leds-gpio

[Pavel Machek]

[-- Attachment #1: Type: text/plain, Size: 1591 bytes --]

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

[-- Attachment #2: signature.asc --]
[-- Type: application/pgp-signature, Size: 195 bytes --]