Question

关于DSP28335的CPU 定时器的配置问题

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;
}
能给我解释一下这段程序吗？

Answer 1

CPUFreqInMHz是DSP的实际工作频率，这个参数的单位是MHz，
PeriodInUSec是要定时的时间长度，单位是微秒
定时值＝定时长度/(CPU的周期）＝定时长度×CPU的频率
Timer->RegsAddr->PRD.all= temp 向定时器周期寄存器赋值

Timer->RegsAddr->TPR.all = 0;
Timer->RegsAddr->TPRH.all = 0；
上面两句是配置定时器预定标寄存器，每个定时器源时钟周期TIM（定时器计数器）减一

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
上面这五句是配置定时器控制寄存器，TSS写1，停止定时器；TRB写1，使能定时器重新装载；SOFT=0、FREE=0是配置CPU定时器仿真模式；TIE写1，CPU定时器中断使能。

以上是我的理解，我也是刚学，如有错误，还望高三指点