def command(self, cmd_code, cmd_data, timeout):
        """Send a host command and return the chip response.

        """
        log.log(logging.DEBUG-1, self.CMD[cmd_code]+" "+hexlify(cmd_data))

        frame = bytearray([0xD4, cmd_code]) + bytearray(cmd_data)
        frame = bytearray([0xFF, 0x00, 0x00, 0x00, len(frame)]) + frame

        frame = self.ccid_xfr_block(frame, timeout)
        if not frame or len(frame) < 4:
            log.error("insufficient data for decoding chip response")
            raise IOError(errno.EIO, os.strerror(errno.EIO))
        if not (frame[0] == 0xD5 and frame[1] == cmd_code + 1):
            log.error("received invalid chip response")
            raise IOError(errno.EIO, os.strerror(errno.EIO))
        if not (frame[-2] == 0x90 and frame[-1] == 0x00):
            log.error("received pseudo apdu with error status")
            raise IOError(errno.EIO, os.strerror(errno.EIO))
        return frame[2:-2]
Send a host command and return the chip response.