TMS320F28069的主频问题

对28069芯片选用外部无缘晶振8M，对系统分频配置时，

#define DSP28_DIVSEL   3 // Enable /1 for SYSCLKOUT

#define DSP28_PLLCR   10

 void InitSysCtrl（）

{

XtalOscSel();

InitPll(DSP28_PLLCR, DSP28_DIVSEL);

InitPeripheralClocks();

InitCpuTimers();

}

void InitCpuTimers(void)
{
// CPU Timer 0
// Initialize address pointers to respective timer registers:
CpuTimer0.RegsAddr = &CpuTimer0Regs;
//Clear interrupt flag
CpuTimer0Regs.TCR.bit.TIF = 0;
//Disable CPU_timer interrupt
CpuTimer0Regs.TCR.bit.TIE = 0;
CpuTimer0Regs.TCR.bit.FREE = 0;
//Stop after the next decrement of the TIMH:TIM (hard stop)
CpuTimer0Regs.TCR.bit.SOFT = 0;
// Initialize timer period to maximum:
CpuTimer0Regs.PRD.all = 0xFFFFFFFF;
// Initialize pre-scale counter to divide by 1 (SYSCLKOUT):
CpuTimer0Regs.TPR.all = 79; // (80MHz/1MHz-1)
CpuTimer0Regs.TPRH.all = 0;
// Make sure timer is stopped:
CpuTimer0Regs.TCR.bit.TSS = 0;
// Reload all counter register with period value:
CpuTimer0Regs.TCR.bit.TRB = 0;
// Reset interrupt counters:
CpuTimer0.InterruptCount = 0;
}

按照道理，主频应该为80MHZ，CPUtimer0是1M，但实测后，发现主频是50Mhz