PDC_PTCR_TXTEN
#define PDC_PTSR_TXTEN PDC_PTCR_TXTEN
PUTREG(sc, SPI_PDC_BASE + PDC_PTCR, PDC_PTCR_TXTEN | PDC_PTCR_RXTEN);
at91usart_writereg(sc, US_PDC + PDC_PTCR, PDC_PTCR_TXTEN);
US_PDC + PDC_PTCR, PDC_PTCR_TXTEN);
US_PDC + PDC_PTCR, PDC_PTCR_TXTEN);