code: def sense_dep(self, target):
          
          if target.atr_req[15] & 0x30 == 0x30:
              self.log.warning("must reduce the max payload size in atr_req")
              target.atr_req[15] = (target.atr_req[15] & 0xCF) | 0x20
  
          target = super(Device, self).sense_dep(target)
          if target is None:
              return
  
          if target.atr_res[16] & 0x30 == 0x30:
              self.log.warning("must reduce the max payload size in atr_res")
              target.atr_res[16] = (target.atr_res[16] & 0xCF) | 0x20
  
          return target
docs: Search for a DEP Target in active communication mode.
  
          Because the PN531 does not implement the extended frame syntax
          for host controller communication, it can not support the
          maximum payload size of 254 byte. The driver handles this by
          modifying the length-reduction values in atr_req and atr_res.