SMSC_BULK_DT_WR
usbd_transfer_start(sc->sc_xfer[SMSC_BULK_DT_WR]);
usbd_transfer_stop(sc->sc_xfer[SMSC_BULK_DT_WR]);
[SMSC_BULK_DT_WR] = {
usbd_xfer_set_stall(sc->sc_xfer[SMSC_BULK_DT_WR]);