SK_TXF1_MACCTL
SK_IF_WRITE_2(sc_if, 0, SK_TXF1_MACCTL, SK_TXMACCTL_XMAC_UNRESET);
SK_IF_WRITE_2(sc_if, 0, SK_TXF1_MACCTL, SK_TXMACCTL_XMAC_RESET);