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