SCPDR_TP_SCAN_X
scpdr &= ~SCPDR_TP_SCAN_X; /* pull low to scan */
scpdr |= SCPDR_TP_SCAN_X;
scpdr |= (SCPDR_TP_SCAN_ENABLE | SCPDR_TP_SCAN_X);
scpdr &= ~SCPDR_TP_SCAN_X;