while (!(pSPI -> SPI_SR & AT91C_SPI_TDRE));   /* Wait for Empty Tx Buffer */

void PIO_INIT () {
    pP_M_C -> PMC_PCER = pP_M_C -> PMC_PCER | 0x00000024;     // Enable clocking of SPI and PIO (PIO clk enable for reading input state)                    
    pPIO -> PIO_PDR = 0x80027000;         // disable PA17 I/O for PCK1 out  and PA12,13,14,31 for SPI
    pPIO -> PIO_PER = 0x00240800;         // enable PA21, PA18 and PA11 I/O
    pPIO -> PIO_PPUDR = 0xFFFFFCFF;         // Turn off pull-up resistor  except 8 and 9
    pPIO -> PIO_ODR = 0x200014FF;         // Enable input for PIO PA29, PA12, PA10, PA0-PA7
    pPIO -> PIO_OER = pPIO -> PIO_OER | 0x00240800;        // Enable out for PA11(CAMERA ON/OFF) and PA21 (ON/OFF SDcard) and PA18 (RED_LED)
}

#define SCBR  ((MCK/SPCK))                      /*SPI Baud Rate Divisor */

#define SPCK    18000000                      /* SPI Baud Rate */

#define QUARTZ    20000000

#define FREQ_DIV   10

#define FREQ_MUL   89

#define MCK   (((QUARTZ*(FREQ_MUL+1)/FREQ_DIV))/2)

AT91S_SPI  * pSPI = AT91C_BASE_SPI;

*AT91C_PMC_PCER = 1UL << AT91C_ID_SPI;

AT91S_PMC  *pP_M_C = AT91C_BASE_PMC;