Activate the RF field and probe for a Type A Target.

        The RC-S956 can discover all Type A Targets (Type 1 Tag, Type
        2 Tag, and Type 4A Tag) at 106 kbps. Due to firmware
        restrictions it is not possible to read a Type 1 Tag with
        dynamic memory layout (more than 128 byte memory).

def sense_tta(self, target):
        """Activate the RF field and probe for a Type A Target.

        The RC-S956 can discover all Type A Targets (Type 1 Tag, Type
        2 Tag, and Type 4A Tag) at 106 kbps. Due to firmware
        restrictions it is not possible to read a Type 1 Tag with
        dynamic memory layout (more than 128 byte memory).

        """
        target = super(Device, self).sense_tta(target)
        if target and target.rid_res:
            # This is a TT1 tag. Unfortunately we can only read it if
            # it is a static memory tag. The RCS956 has implemented
            # the same wrong command codes as PN531/2/3 and directly
            # programming the CIU does not work.
            if target.rid_res[0] >> 4 == 1 and target.rid_res[0] & 15 != 1:
                msg = "The {device} can not read this Type 1 Tag."
                self.log.warning(msg.format(device=self))
                return None
        return target