POWER_UP(SPI1 | PIOA);                         // enable clocks to SPI1 in PMC and Port A due to CS line
PIO_BSR_A = (SPI_MOSI_1B | SPI_MISO_1B | SPI_CLK_1B);
PIO_PDR_A = (SPI_MOSI_1B | SPI_MISO_1B | SPI_CLK_1B); // enable SPI pins
PIO_PER_A = (SPI_CS0_1B);                      // configure CS0 for SW control
PIO_SODR_A = (SPI_CS0_1B);
PIO_OER_A = (SPI_CS0_1B);

SPI_MR_1 = (SPI_MSTR | MODFDIS | SPI_CS_0);    // set SPI mode
SPI_CSR0_1 = (SPI_CPOL | SPI_8_BITS | (((MASTER_CLOCK + 6000000/2)/6000000) << 8)); // set speed 6MHz
SPI_CR_1 = SPIEN;                              // enable

PIO_CODR_A = SPI_CS0_1B;                       // assert CS line

SPI_TDR_1 = ucCommand;                         // send a byte
while (!(SPI_SR_1 & SPI_RDRF)) {};             // wait until tx byte has been sent and rx byte has been completely received
ucRxData = SPI_RDR_1;                          // read the returned byte

PIO_SODR_A = SPI_CS0_1B;                       // negate CS line