The Yocto-Color and RGBW leds

The Yocto-Color and RGBW leds

The Yocto-Color-V2 was designed in the beginning of 2016 to drive those small RGB leds that one can wire serially and address individually, the most well known ones being the Adafruit NEOPIXEL leds. Meanwhile appeared the RGBW leds, which can emit not only red, green, and blue but also white and which are, for sure, compatible with the classic RGB leds. Good news: we just published a new firmware for the Yocto-Color-V2 which drives these RGBW leds.

Left: RGB leds, right: RGBW leds, note the half-moon shaped white led part
Left: RGB leds, right: RGBW leds, note the half-moon shaped white led part

How it works

It's now dead simple to make a Yocto-Color-V2 work with RGBW leds. Connect your leds and configure their type by using the VirtualHub, for example. That's it.

Use the VirtualHub to configure the type of leds
Use the VirtualHub to configure the type of leds

Managing the white part of the leds is done automatically, we opted for a simple but efficient (R,G,B) → (R,G,B,W) transfer function.

The transfer function
The transfer function

We assign to the white led the minimum of the three red, green, and blue values and we assign to the red, green, and blue leds the R, G, B, values minus the white value. Thus, all the control API stays strictly the same. If you have a software that drives the Yocto-Color-V2 with RGB leds, it will work as well with RGBW leds.

The interest of these RGBW leds

These RGBW leds have a few advantages compared to the simple RGB leds.

  • Whites are more natural and more uniform
  • At full power, that is pure white, they consume appreciably less: ~20mA per RGBW led instead of 35mA for an RGB led.
  • Consuming less, they also heat less.

What you must know

As nothing is really magical in this world, here are a few points you should remember if you don't want to spend too much time in case a problem occurs.

  • The supported RGBW leds are the SK6812RGBW leds and compatible
  • You need at least firmware 30526 for it to work.
  • You can't control yourself the white part of the leds.
  • You can't mix RGB leds and RGBW leds, which means that if you want to use RGBW leds with the Yocto-Color-V2, you must split the module into two to remove the two original RGB leds. Nothing too complicated, as shown in the Yocto-Color-V2 demo video.
  • These RGBW leds have several flavors of white: "Cold", "Warm" and "Natural". Currently, the Yocto-Color-V2 doesn't make a difference and treats them in the same way.
  • If you don't obtain the intended colors, check that you have configured the right type of leds before you panic.

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