DAC7558使用的出现的困惑

#include "DSP281x_Device.h"     // DSP281x Headerfile Include File
#include "DSP281x_Examples.h"   // DSP281x Examples Include File
#include "math.h"
//#include "math.h"
// Prototype statements for functions found within this file.
interrupt void cpu_timer0_isr(void);
#define PI 3.1415926
#define N  100
float Sin_a[N];
Uint16  Simu_a[N];
Uint32  Data_E;
Uint32  Data_T[24];
int     flag;
int     p,q;
void Simu_sin(void); //SIN波形转换函数
void Data_handle(Uint16 Data_Row);
void Xmit_Init(Uint32 Data);
//void TX(void);

void main(void)
{
   Uint32 i=0;
   Uint32 j=0;
// Step 1. Initialize System Control:
// PLL, WatchDog, enable Peripheral Clocks
// This example function is found in the DSP281x_SysCtrl.c file.
   InitSysCtrl();

// Step 2. Initalize GPIO:// This example function is found in the DSP281x_Gpio.c file and
// illustrates how to set the GPIO to it's default state.
// InitGpio();  // Skipped for this example    EALLOW;
   GpioMuxRegs.GPAMUX.bit.C3TRIP_GPIOA15=0;  //A15->F10  SDIN
   GpioMuxRegs.GPAMUX.bit.C2TRIP_GPIOA14=0;   //A14->F11  SCLK
   GpioMuxRegs.GPAMUX.bit.C1TRIP_GPIOA13=0;   //A13->F12  SYNC
   //GpioMuxRegs.GPAQUAL.bit.QUALPRD=0xff;
   GpioMuxRegs.GPADIR.bit.GPIOA15=1;
   GpioMuxRegs.GPADIR.bit.GPIOA14=1;
   GpioMuxRegs.GPADIR.bit.GPIOA13=1;
   GpioDataRegs.GPASET.bit.GPIOA15=1;
   //GpioDataRegs.GPASET.bit.GPIOA14=1;
   GpioDataRegs.GPASET.bit.GPIOA13=1;
   EDIS;
// Step 3. Clear all interrupts and initialize PIE vector table:
// Disable CPU interrupts   DINT;

// Initialize the PIE control registers to their default state.
// The default state is all PIE interrupts disabled and flags
// are cleared. // This function is found in the DSP281x_PieCtrl.c file.
   InitPieCtrl();
  // Disable CPU interrupts and clear all CPU interrupt flags:
   IER = 0x0000;
   IFR = 0x0000;

// Initialize the PIE vector table with pointers to the shell Interrupt// Service Routines (ISR). // This will populate the entire table, even if the interrupt
// is not used in this example.  This is useful for debug purposes.
// The shell ISR routines are found in DSP281x_DefaultIsr.c.
// This function is found in DSP281x_PieVect.c.
   InitPieVectTable();

// Interrupts that are used in this example are re-mapped to
// ISR functions found within this file.    EALLOW;  // This is needed to write to EALLOW protected registers
   PieVectTable.TINT0 = &cpu_timer0_isr;
   EDIS;    // This is needed to disable write to EALLOW protected registers

// Step 4. Initialize all the Device Peripherals:
// This function is found in DSP281x_InitPeripherals.c
// InitPeripherals(); // Not required for this example
   Simu_sin();
   InitCpuTimers();   // For this example, only initialize the Cpu Timers

// Configure CPU-Timer 0 to interrupt every second:
// 100MHz CPU Freq, 1 second Period (in uSeconds)
   ConfigCpuTimer(&CpuTimer0, 150, 100);

// Step 5. User specific code, enable interrupts:

// Enable CPU INT1 which is connected to CPU-Timer 0:
  IER |= M_INT1;

// Enable TINT0 in the PIE: Group 1 interrupt 7
  PieCtrlRegs.PIEIER1.bit.INTx7 = 1;

// Enable global Interrupts and higher priority real-time debug events:
   EINT;   // Enable Global interrupt INTM
   ERTM;   // Enable Global realtime interrupt DBGM

// Step 6. IDLE loop. Just sit and loop forever (optional):

   while(1)
   {
      for(i=0;i<100;i++)
  {
       EALLOW;
    GpioDataRegs.GPACLEAR.bit.GPIOA13=1; //片选线拉低
    GpioDataRegs.GPACLEAR.bit.GPIOA15=1;  //数据线拉低
    GpioDataRegs.GPACLEAR.bit.GPIOA14=1; //时钟线拉低(高）
       EDIS;
       Data_handle(0xC180);
       Xmit_Init(Data_E);
       flag=0;
       StartCpuTimer0();            //启动时钟
       do{;}
       while(!(flag==25));
       StopCpuTimer0(); //转换完成，停止时钟
       EALLOW;
           GpioDataRegs.GPASET.bit.GPIOA13=1;  //片选线拉高
       GpioDataRegs.GPACLEAR.bit.GPIOA14=1; //时钟线拉（高）
       GpioDataRegs.GPACLEAR.bit.GPIOA15=1;  //数据线拉低
       EDIS;

       for(j=0;j<5000;j++)
       {;}
      }
   }

}

interrupt void cpu_timer0_isr(void)
{

   CpuTimer0.InterruptCount++;
   EALLOW;
   GpioDataRegs.GPATOGGLE.bit.GPIOA14=1;
   EDIS;

   if(GpioDataRegs.GPADAT.bit.GPIOA14 == 1)
   {
   if(Data_T[flag])
              {
               EALLOW;
               GpioDataRegs.GPADAT.bit.GPIOA15=1; //第23-i位数据为1
               EDIS;
               p++;
              }
       else
             {
               EALLOW;
               GpioDataRegs.GPADAT.bit.GPIOA15=0; //第23-i位数据为0
               EDIS;

             }
       flag++;

   }
   // Acknowledge this interrupt to receive more interrupts from group 1
   PieCtrlRegs.PIEACK.all = PIEACK_GROUP1;
}

//Sin波形转换
void Simu_sin(void)
{
  int i=0;
  float j=0;
  for(i=0;i<N;i++)
  {
   j = (float)(i)/100*2*PI;
   Sin_a[i]=sin(j);
   Simu_a[i]=(Uint16)((2048*Sin_a[i]+2048))<<4;
  }
}
//数据整合函数
//入口函  DAC芯片的数据位
//函数返回值 发送给DAC芯片的数据
void Data_handle(Uint16 DataRow)
{
 Uint16 Data_temp_H;
 Uint16 Data_temp_L;
 Uint32 Data_temp=0x00000000;
 Data_temp_L=DataRow&0xfff0;
 Data_temp_H=0x000E;
    Data_temp=(Data_temp+Data_temp_H)<<16;
    Data_E=Data_temp+Data_temp_L;
 //return Data_temp;
}

void Xmit_Init(Uint32 Data)
{
 Uint32 Data_Handle;

 int i;
 for(i=0;i<24;i++)
 {
     Data_Handle=0x00000001;

     Data_Handle=Data_Handle<<(23-i);
     Data_T[i]=Data&Data_Handle;
 }