dsp28335 定时器时间如何设置到ns级

dsp28335 定时器时间如何设定为ns级别，因为150MHZ应该最小为6ns，例程中使用了结构体编程，下面就是，可以看到**PeriodInUSec = Period;**语句就是限制住了最小是1微秒.但是我想应用于ns级的定时。

void ConfigCpuTimer(struct CPUTIMER_VARS *Timer, float Freq, float Period)
{
    Uint32     temp;

    // Initialize timer period:
    Timer->CPUFreqInMHz = Freq;
    Timer->PeriodInUSec = Period;
    temp = (long) (Freq * Period);
    Timer->RegsAddr->PRD.all = temp;

    // Set pre-scale counter to divide by 1 (SYSCLKOUT):
    Timer->RegsAddr->TPR.all  = 0;
    Timer->RegsAddr->TPRH.all  = 0;

    // Initialize timer control register:
    Timer->RegsAddr->TCR.bit.TSS = 1;      // 1 = Stop timer, 0 = Start/Restart Timer
    Timer->RegsAddr->TCR.bit.TRB = 1;      // 1 = reload timer
    Timer->RegsAddr->TCR.bit.SOFT = 0;
    Timer->RegsAddr->TCR.bit.FREE = 0;     // Timer Free Run Disabled
    Timer->RegsAddr->TCR.bit.TIE = 1;      // 0 = Disable/ 1 = Enable Timer Interrupt

    // Reset interrupt counter:
    Timer->InterruptCount = 0;
}

period可以为小数