Question of interface to a SSI / SPI ADC question

Code:

int main(void)
{
unsigned long ulDataTx[NUM_SSI_DATA]=0;
unsigned long ulDataRx[NUM_SSI_DATA];
unsigned long ulindex;
unsigned long i;
tContext sContext;
char cText[16];

SysCtlClockSet(SYSCTL_SYSDIV_4 | SYSCTL_USE_PLL | SYSCTL_XTAL_16MHZ | SYSCTL_OSC_MAIN);

// display in LCD
CFAL96x64x16Init();
GrContextInit(&sContext, &g_sCFAL96x64x16);
GrContextForegroundSet(&sContext, ClrWhite);
GrContextFontSet(&sContext, &g_sFontFixed6x8);

GrStringDraw(&sContext,"SSI3 ->", -1,1, 5, 0);
GrStringDraw(&sContext,"Mode: SPI", -1,1, 15, 0);
GrStringDraw(&sContext,"Data: 16-bit", -1,1, 25, 0);

// show the initial data (16 bits)

for(i=0;i<NUM_SSI_DATA;i++)
{
usprintf(cText, "%d ", ulDataRx[i]);   //show output
GrStringDraw(&sContext, cText, -1,i*5, 40, 1);
}

SysCtlPeripheralEnable(SYSCTL_PERIPH_SSI3);
SysCtlPeripheralEnable(SYSCTL_PERIPH_GPIOH);

// Configure the pin muxing for SSI3 functions on port H
GPIOPinConfigure(GPIO_PH0_SSI3CLK);
GPIOPinConfigure(GPIO_PH2_SSI3RX);
GPIOPinConfigure(GPIO_PH3_SSI3TX);
GPIOPinTypeGPIOOutput(GPIO_PORTH_BASE, GPIO_PIN_1);//sherry

GPIOPinTypeSSI(GPIO_PORTH_BASE, GPIO_PIN_0 | GPIO_PIN_2 | GPIO_PIN_3); //sherry GPIO_PIN_1 |
GPIOPinWrite(GPIO_PORTH_BASE,GPIO_PIN_1,GPIO_PIN_1); //禁用功能，禁用片選FLASH，向指定腳寫入值

SSIClockSourceSet(SSI3_BASE,SSI_CLOCK_SYSTEM);
SSIConfigSetExpClk(SSI3_BASE, SysCtlClockGet(), SSI_FRF_MOTO_MODE_0,
SSI_MODE_MASTER, 2000000, 16); //2MHz,16bits

SSIEnable(SSI3_BASE);

//GPIOPinWrite(GPIO_PORTD_BASE,GPIO_PIN_1,GPIO_PIN_1);

//
// Read any residual data from the SSI port. This makes sure the receive
// FIFOs are empty, so we don't read any unwanted junk. This is done here
// because the SPI SSI mode is full-duplex, which allows you to send and
// receive at the same time. The SSIDataGetNonBlocking function returns
// "true" when data was returned, and "false" when no data was returned.
// The "non-blocking" function checks if there is any data in the receive
// FIFO and does not "hang" if there isn't.

while(1)

{
unsigned long get_data;
GPIOPinWrite(GPIO_PORTH_BASE,GPIO_PIN_1,0); //ENABLE ADC
SSIDataPut(SSI3_BASE,0x00);
SSIDataGet(SSI3_BASE,&get_data);
//send_byte(0x00);
//SSIDataPut(SSI3_BASE, 0x00); //PUT OUT RANDOM DATA
while((1 == HWREGBITW(GPIO_PORTH_BASE + SSI_O_SR,4))); //WAIT FOR SSI TO BE IDLE
GPIOPinWrite(GPIO_PORTH_BASE,GPIO_PIN_1,GPIO_PIN_1); //DISABLE ADC

for(i=0;i<NUM_SSI_DATA;i++)
{
SSIDataPut(SSI3_BASE,0xFF);
SSIDataGet(SSI3_BASE,&get_data);
ulDataRx[i] = get_data;
usprintf(cText, "%d ", ulDataRx[i]);//show output
GrStringDraw(&sContext, cText, -1,i*5, 50, 1);

}

}

// Determine if the SSI is busy.

return((HWREG(SSI3_BASE + SSI_O_SR) & SSI_SR_BSY) ? true : false);
}