求大家帮忙解释一段程序，新手

只看该作者 · 2014-4-3 15:07

#include "DSP2833x_Device.h"    // DSP2833x Headerfile Include File
#include "DSP2833x_Examples.h" // DSP2833x Examples Include File

#if (CPU_FRQ_150MHZ)
  #define CPU_CLK 150e6
#endif
#if (CPU_FRQ_100MHZ)
  #define CPU_CLK 100e6
#endif
#define PWM_CLK 10e3             // If diff freq. desired, change freq here.
#define SP       CPU_CLK/(2*PWM_CLK)
#define TBCTLVAL  0x200E             // Up-down cnt, timebase = SYSCLKOUT

void EPwmSetup()
{
InitEPwm1Gpio();
EPwm1Regs.TBSTS.all=0;
EPwm1Regs.TBPHS.half.TBPHS=0;
EPwm1Regs.TBCTR=0;

EPwm1Regs.CMPCTL.all=0x50;       // Immediate mode for CMPA and CMPB
EPwm1Regs.CMPA.half.CMPA =SP/2;
EPwm1Regs.CMPB=SP/4;

EPwm1Regs.AQCTLA.all=0x60;       // EPWMxA = 1 when CTR=CMPA and counter inc
                                    // EPWMxA = 0 when CTR=CMPA and counter dec
EPwm1Regs.AQCTLB.all=0x60;
// EPwm1Regs.AQCTLB.all=0;
EPwm1Regs.AQSFRC.all=0;
EPwm1Regs.AQCSFRC.all=0;

EPwm1Regs.DBCTL.all=0x23;       // EPWMxB is inverted
EPwm1Regs.DBRED=0;
EPwm1Regs.DBFED=0;

EPwm1Regs.TZSEL.all=0;
EPwm1Regs.TZCTL.all=0;
EPwm1Regs.TZEINT.all=0;
EPwm1Regs.TZ标志寄存器.all=0;
EPwm1Regs.TZCLR.all=0;
EPwm1Regs.TZFRC.all=0;

EPwm1Regs.ETSEL.all=0;          // Interrupt when TBCTR = 0x0000
EPwm1Regs.ET标志寄存器.all=0;
EPwm1Regs.ETCLR.all=0;
EPwm1Regs.ETFRC.all=0;

EPwm1Regs.PCCTL.all=0;

EPwm1Regs.TBCTL.all=0x0010+TBCTLVAL; // Enable Timer
EPwm1Regs.TBPRD=SP;

}
28335dsp的主频是150MHZ,为什么他还要写一个100MHZ的？CPU_FRQ和CPU_CLK有什么区别？是什么寄存器？PWM_CLK、SP、TBCTLVAL又是什么寄存器？问题有点多，谢谢回答。