Phlips Hue - RGB Color Feedback - Zigbee

[Jose]

Hello everyone,
I am trying to read the color status of a Philips RGB lamp with the Zigbee gateway.
Looking at the link: https://kb.logicmachine.net/libraries/zigbee/

I have been able to get the On/Off status, color temperature, but I am not able to read the RGB status.I don't understand that about xy and then being able to convert it to 3 bytes to use it on KNX screens.
Can anybody help me?
Thank you so much in advance,

[admin]

Try using xy_to_rgb from user.hue v2.lua: https://forum.logicmachine.net/showthrea...50#pid6250

[Joep]

Code:

RGB = event.getvalue()

-- Norm of RGB values
R = bit.rshift(bit.band(RGB, 0xFF0000), 16)
G = bit.rshift(bit.band(RGB, 0x00FF00), 8)
B = bit.band(RGB, 0x0000FF)

Red =    R / 255
Green = G / 255
Blue = B / 255

-- Gamma correction
if Red > 0.04045 then
  Red = ((Red + 0.055) / (1 + 0.055))^2.4
else
  Red = Red / 12.92
end

if Green > 0.04045 then
  Green = ((Green + 0.055) / (1 + 0.055))^2.4
else
  Green = Green / 12.92
end

if Blue > 0.04045 then
  Blue = ((Blue + 0.055) / (1 + 0.055))^2.4
else
  Blue = Red / 12.92
end

-- Coversion RGB > XY
X = Red * 0.649926 + Green * 0.103455 + Blue * 0.197109
Y = Red * 0.234327 + Green * 0.743075 + Blue * 0.022598
Z = Green * 0.053077 + Blue * 1.035763

x = X / (X+Y+Z)
y = Y / (X+Y+Z)

-- Coversion XY > CCT
n = (x - 0.3320) / (0.1858 - y)
cct = math.floor((-449 * ((x - 0.332) / (y - 0.1858))^3) + (3525 * ((x - 0.332) / (y - 0.1858))^2) - (6823.3 * ((x - 0.332) / (y - 0.1858))) + (5520.33))

log(cct)

[stianj]

Try using xy_to_rgb from user.hue v2.lua: https://forum.logicmachine.net/showthrea...50#pid6250

I'm trying to use xy_to_rgb from user.hue v2.lua. But I can't be doing it right. I have copied the function into common functions. Then I have in the event script:

Code:

xy = zb.cmdsync('getxy', addr)
rgb = xy_to_rgb(xy['x'],xy['y'])
log(rgb)

But I get the excact same rgb value wether I have red or blue light. (255,0,0) or (0,0,255) gives the same rgb value. But the lamp is red or blue correctly. For colours without blue the result makes sense I think, but it seems like blue and red is mixed up somehow.

Value of variable rgb is 16711680 for both (255,0,0) and (0,0,255)...

I can see that the x and y values differ (45913,19614) for red and (8880,2613) for blue - so the result shouldn't be equal...

Any hints?

[stianj]

Well, looking more into this I now understand that the xy coordinates should be less than 1 - and that's the main problem. Don't know where these numbers come from, or what I can do with them... Help!

[admin]

Use this conversion function:

Code:

function xytorgb(x, y, level)
  local function revgamma(v)
    if v <= 0.0031308 then
      return v * 12.92
    else
      return (1 + 0.055) * math.pow(v, (1 / 2.4)) - 0.055
    end
  end

  local function clampconvert(v, max)
    v = math.max(0, v * 255 / max)
    v = math.min(255, v)
    return math.round(v)
  end

  local x = x / 0xFFFE
  local y = y / 0xFFFE
  local z = 1 - x - y

  local Y = math.min(254, level) / 254
  local X = (Y / y) * x
  local Z = (Y / y) * z

  local r = revgamma(3.2404542 * X - 1.5371385 * Y - 0.4985314 * Z)
  local g = revgamma(-0.9692660 * X + 1.8760108 * Y + 0.0415560 * Z)
  local b = revgamma(0.0556434 * X - 0.2040259 * Y + 1.0572252 * Z)

  local max = math.max(r, g, b)

  r = clampconvert(r, max)
  g = clampconvert(g, max)
  b = clampconvert(b, max)

  return r * 0x10000 + g * 0x100 + b
end

x = 45913
y = 19614
level = 254

rgb = xytorgb(x, y, level)
log(rgb)

You also need to pass the light level (0..254) for the conversion to work.

[stianj]

Thank you so much! This works nicely! 

Can I ask why getxy() returns not xy?

But I think I have uncovered a bug in the Mosaic RGBW dimmer (6 byte DALI) widget. It seems it expects 0-255 values, but according to this:

https://support.knx.org/hc/en-us/article...2631105682

(and my Gira devices...) the 6 byte DPT 251.600 should have 0-100 as value for the different colours. Unlike 232.600 which is 0-255... Yay for consistency from KNX...

Unless I'm mistaken (which I very much could be...) it would be awesome if this could be fixed in the next FW release

[admin]

The actual range is 0..255 which is treated as 0..100%. Notice the resolution is ~0.4% (100/255).

[stianj]

Might be... But Gira sends (and expects) 0-100. But that might be their bug, I don't have anything else to compare with.

(But why is the DPT 232.600 showing expected value to be 0-255, while DPT 251.600 shows 0-100 in the specifications?)

---

Seems atleast a MDT Dali controller does the same: https://community.openhab.org/t/rgbw-col...600/150055