智能车制作

标题: PWM [打印本页]

作者: lvyanghui 时间: 2012-4-4 14:58
标题: PWM
PWM0口就是不出波形，真的不知道为什么了！  求大侠们帮助啊！！！

/*------------------------------------------------------------------------*/
#include <hidef.h>    /* common defines and macros */
#include <MC9S12XS128.h>    /* derivative information */
//#pragma LINK_INFO DERIVATIVE "mc9s12xs128"

void SetBusCLK_48M(void)
{
CLKSEL=0X00; //disengage PLL to system
PLLCTL_PLLON=1; //turn on PLL
SYNR =0xc0 | 0x05;
REFDV=0x80 | 0x01;
POSTDIV=0x00;    //pllclock=2*osc*(1+SYNR)/(1+REFDV)=96MHz;
_asm(nop);       //BUS CLOCK=48M
_asm(nop);
while(!(CRGFLG_LOCK==1)); //when pll is steady ,then use it;
CLKSEL_PLLSEL =1;       //engage PLL to system;
}
void PWM_init(void) //脉宽调制模块的初始化
{

  //SB,B for ch2367
  //SA,A for ch0145
  PWME_PWME0=0X00;
  PWMPRCLK=0X44; // 0100 0100 A=B=48M/16= 3M
  PWMSCLA=150;
  PWMSCLB=150;  // SB=B/2/150=10K
  PWMCLK_PCLK0=1;  //  PWM3---SB
  PWMPOL_PPOL0=1;  // duty = high time
  PWMCAE_CAE0=0;  //  left-aligned
  PWMCTL=0X00;
  PWMPER0=100;  // frequency = SB/100 = 100Hz 10ms
  PWMDTY0=50;  //  duty cycle =
  PWME_PWME0=1;
}

void main(void) {
  /* put your own code here */
  unsigned char LedCnt=0;

  SetBusCLK_48M(); // 设定总线频率

  PWM_init();

  EnableInterrupts;
  for(;;) {


  } /* wait forever */
  /* please make sure that you never leave this function */
}

作者: 451506709 时间: 2012-4-4 16:54
好像你的PWMCLK寄存器设置错了，你再仔细看看

作者: 风行蟹 时间: 2012-4-4 17:39
你的PWM波形输出是PWM0，用示波器去测PP0端口。我试过了，对的。周期也对的！！希望你可以！！

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