slaveName = "5" -- number of button to assign to
masterID = 0
outputBool = false -- default (off) state of redstone power for spawner, false means off
masterActive = false
lastmessage = "foo" -- meaningless message

function testMaster(pID, pMessage)
  if message == "KKRNBTNMaster" then
    rednet.send(pID, slaveName)
    masterID = pID
    print("Discovered Master with ID: " .. pID)
    return true
  end
end


function testMessage()
  id, message = rednet.receive()
  if message == "t" then
    if id == masterID then
      outputBool = not outputBool
      setRedstone(outputBool)
      lastmessage = message
    end
  else
    if message ~= lastmessage then
      masterActive = false
    end
    if not masterActive then
      testMaster(id, message)
      masterActive = true
      lastmessage = message
    end
  end
end

function setRedstone(state)
  print("Setting Redstone to: " .. tostring(state))
  redstone.setOutput("back", state)
end

setRedstone(outputBool)

rednet.open("top")

while true do
  testMessage()
end