docs: def cum_serial(self, raw,rev=0):
      """ Cumulate serial data
          and return times(int)
          計算數據重複（持續）次數
      """
      org = raw[1:]
      diff = raw[:-1]
      result = []
      for i in xrange(len(org)):
        result.append(self.high_or_low(org[i], diff[i],rev))
  
      times = 0
      try:
        if result[-1] == result[-2]:
          signal = result[-1]
          re_signal = result[:]
          try:
            while signal == re_signal[-1]:
              re_signal.pop()
              times += 1
          except:
            pass
        else:
          times += 1
      except:
        times = '?'
  
      if self.debug:
        for i in result:
          print i
  
      self.debug_print(times)
      return times