startup

function doRsPulse()
  rs.setOutput("back", true)
  sleep(0.1)
  rs.setOutput("back", false)
end

local itemDetRsCount = 0
local itemDetRsCountThresh = 3

function checkAndPulse()
  if rs.getInput("bottom") then
    itemDetRsCount = itemDetRsCount + 1
  else
    itemDetRsCount = 0
  end

  if itemDetRsCount >= itemDetRsCountThresh then
    doRsPulse()
    itemDetRsCount = 0
  end

  sleep(0.2)
end

while true do checkAndPulse() end