ss.lua

-- curl -d '' 'http://192.168.100.169/ss.lua?p=11101001001000111&bpm=200'

local function stop()
  print("Stopped.")
  if timer then
    timer:unregister()
    timer = nil
  end
  gpio.write(0,0)
  pattern = nil
  collectgarbage()
end


local beat = 0
local ratio = 4

local function tap()
  if beat == 0 then
    gpio.write(0,tonumber(pattern:sub(1,1)))
    pattern = pattern:sub(2)
  elseif beat == 1 then
    gpio.write(0,0)
  end
  beat = beat + 1
  if beat >= ratio then
    beat = 0
    if pattern == "" then
      stop()
    end
  end
end


local function onReceive(connection, req)

  local p = req:match("p=([01]+)")
  if p then pattern = p end

  p = req:match("r=([1-9])")
  if p then ratio = tonumber(p) end

  p = req:match("bpm=([0-9]+)")
  if p and pattern then

    local ms = req:match("ms=([[0-9]+)")
    if ms then ms = ms*p ratio = (15000+ms/2)/ms end

    if not timer then
      print("Started bpm="..p)
      timer = tmr.create()
    else
      print("New bpm="..p)
      timer:unregister()
    end

    tap()
    p = p*ratio
    timer:alarm((15000+p/2)/p, tmr.ALARM_AUTO, tap)
  else

    stop()
  end

  connection:send("HTTP/1.1 204 No Content\r\nAccess-Control-Allow-Origin: *\r\nAccess-Control-Allow-Methods: POST,OPTIONS\r\nConnection: keep-alive\r\n\r\n")
  collectgarbage()
end


return function(connection, req)
  connection:on("receive", onReceive)
  onReceive(connection, req)
end