WoWInterface - Pulsing background?

Trying to make the background of my frame pulsing red, but it takes a couple of big steps from black to bright red, but then never comes back down to black. I can see the value of r climb from 0 to 1 and back down to 0, but the frame color never changes after it hits red. Thoughts?

Code:

local seconds = 0.5

local total = 0



local r = 0

local rud = 0.2



SPHowFrame:SetScript("OnUpdate", function(self, elapsed)

        total = total + elapsed

        if total > seconds then

      local r = getRedColor()

      print (r)

      self.texture = nil

      self.texture = self:CreateTexture(nil,"BACKGROUND")

      self.texture:SetColorTexture(r, 0, 0)

      self.texture:SetAllPoints(self)

      self.texture = t

      total = 0

        end

end)





function getRedColor()

  r = r + rud

  if r > 1 then

      rud = rud * -1

      r=1

  end 

  if r < 0 then 

      rud = rud * -1

      r=0

  end 

  

  return r

end

local SPHowFrame = CreateFrame("Frame", nil, UIParent)
SPHowFrame:SetSize(50, 50)
SPHowFrame:SetPoint("CENTER")
SPHowFrame.texture = SPHowFrame:CreateTexture()
SPHowFrame.texture:SetAllPoints()
SPHowFrame.texture:SetTexture("Interface/Buttons/WHITE8X8")
 
local seconds = 0.5
local total = 0
 
local r = 0
local rud = 0.2
 
SPHowFrame:SetScript("OnUpdate", function(self, elapsed)
    total = total + elapsed
    if total > seconds then
      local r = getRedColor()
      print (r)
      self.texture:SetColorTexture(r, 0, 0)
      total = 0
    end
end)
 
 
function getRedColor()
   r = r + rud
   if r > 1 then
      rud = rud * -1
      r=1
   end 
   if r < 0 then 
      rud = rud * -1
      r=0
   end 
   
   return r
end