RGB relative dimming from KNX

[admin]

Use this event script for 4-bit object. Change R/G/B addresses as needed and modify step and delay to change the dimming speed and smoothness.

Code:

raddr = '32/1/1' -- red value address
gaddr = '32/1/2' -- green value address
baddr = '32/1/3' -- blue value address
step = 0.05 -- step side
delay = 0.3 -- delay between steps

value = event.getvalue()
up = bit.band(value, 0x08) == 0x08
stop = bit.band(value, 0x07) == 0

if stop then
  return  
end

-- get value and convert from 0..100 to 0..255
r = grp.getvalue(raddr) * 2.55
g = grp.getvalue(gaddr) * 2.55
b = grp.getvalue(baddr) * 2.55

function rgbtohsv(r, g, b)
  local max, min, d, h, s, v

  max = math.max(r, g, b)
  min = math.min(r, g, b)
  d = max - min
  s = max == 0 and 0 or (d / max)
  v = max / 255

  if max == min then
    h = 0
  elseif max == r then
    h = (g - b) + d * (g < b and 6 or 0)
    h = h / (6 * d)
  elseif max == g then
    h = (b - r) + d * 2
    h = h / (6 * d)
  elseif max == b then
    h = (r - g) + d * 4
    h = h / (6 * d)
  end

  return h, s, v
end

function hsvtorgb(h, s, v)
  local r, g, b, i, f, p, q, t, z

  i = math.floor(h * 6)
  f = h * 6 - i
  p = v * (1 - s)
  q = v * (1 - f * s)
  t = v * (1 - (1 - f) * s)
  z = i % 6

  if z == 0 then
    r = v
    g = t
    b = p
  elseif z == 1 then
    r = q
    g = v
    b = p
  elseif z == 2 then
    r = p
    g = v
    b = t
  elseif z == 3 then
    r = p
    g = q
    b = v
  elseif z == 4 then
    r = t
    g = p
    b = v
  elseif z == 5 then
    r = v
    g = p
    b = q
  end

  r = math.round(r * 255)
  g = math.round(g * 255)
  b = math.round(b * 255)

  return r, g, b
end

function rgbstep(r, g, b, up, step)
  local h, s, v = rgbtohsv(r, g, b)
  local v2 = up and math.min(1, v + step) or math.max(0, v - step)
  
  if v == v2 then
    return
  end

  return hsvtorgb(h, s, v2)
end

while true do
  r, g, b = rgbstep(r, g, b, up, step)
  if r then
    grp.write(raddr, r, dt.uint8)
    grp.write(gaddr, g, dt.uint8)
    grp.write(baddr, b, dt.uint8)
  else
    break
  end

  os.sleep(delay)
  newvalue = grp.getvalue(event.dst)
  if value ~= newvalue then
    break
  end
end