dreg sample

      # Overall system interface
      self.address = RegStorage(7, resettable=True, description="""Write to update the USB Address.

          When you receive a `SET_ADDRESS` packet from the host, update the address by writing it into
          this field.  Otherwise, the USB controller will ignore all future packets.

          This value will be reset to 0 when the host issues a USB reset.
          """)
####
      # SETUP endpoint Register Interface
      self.data = data = RegStatus(8, description="This FIFO contains the contents of the most recent SETUP packet")
      self.status = status = RegStatus(
          Field("have", description="`1` if there is data in the FIFO."),
          Field("is_in", description="`1` if an IN stage was detected."),
          Field("epno", size=4, description="The destination endpoint for the most recent SETUP token."),
          Field("pend", description="`1` if there is an IRQ pending."),
          Field("data", description="1` if a DATA stage is expected."),
          description="Status and diagnostic information about the SETUP handler",
      )
      self.ctrl = ctrl = RegStorage(
          Field("advance", description="Write a `1` here to advance the `DATA` FIFO.", pulse=True),
          Field("handled", description="Write a `1` here to indicate SETUP has been handled.", pulse=True),
          Field("reset", description="Write a `1` here to reset the `SETUP` handler.", pulse=True),
      )