os.startTimer not doing the time I specify

for k,v in pairs(peripheral.getNames()) do
t = peripheral.getType(v)
if t == "BigReactors-Reactor" then
  r = peripheral.wrap(v)
  --print("found reactor!")
elseif t == "monitor" then
  m = peripheral.wrap(v)
  --print("found monitor!")
end
end
b = {}
tno = {"getControlRodName","getCoolantType","getControlRodLevel","getControlRodLocation","getHotFluidType"}
m.clear()
m.setCursorPos(1,0)
m.setTextScale(1)
function mprint(text)
xx,yy = m.getCursorPos()
m.setCursorPos(1,yy+1)
m.write(text)
end
function addButton(x,y,text,func)
b[x..y] = {x,y,text,func}
end
function testTable(k,t)
for i,y in pairs(t) do
  if y == k then
   return true
  end
end
return false
end
function rawDiagnostics()
mprint("raw diagnostics!")
for k,v in pairs(r) do
  tf = string.sub(k,0,2)
  if tf == "ge" or tf == "is" then
   if testTable(k,tno) == false then
    x,y,z = v()
    str = x
    if y then
	 str = str..","..y
    end
    if z then
	 str = str..","..z
    end
    mprint(k..": "..tostring(str))
   else
    mprint(k..": args needed")
   end
  end
end
end
function checkxy(x, y)
   for name, data in pairs(B)/>/> do
	  if y>=data[2] and  y <= data[2] then
		 if x>=data[1] and x<= data[1]+#tostring(data[3]) then
		    data[4]()
		    return true
		 end
	  end
   end
   return false
end
function toggleActive()
r.setActive(not r.getActive())
end
function draw()
for h,j in pairs(B)/>/> do
  m.setCursorPos(j[1],j[2])
  m.write(j[3])
end
end
function addText(x,y,text)
--b[text] =
end
while true do
b = {}
addButton(2,2,r.getActive(),toggleActive)
m.clear()
draw()
timer = os.startTimer(0.5)
a,side,x,y = os.pullEvent()
if a == "monitor_touch" then
  checkxy(x,y)
elseif a == "timer" then
  timer = os.startTimer(10)
  print("update!",os.time())
end
end