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标题: pwm控制led亮度问题求助！！！ [打印本页]

作者: 风起天阑 时间: 2016-8-2 10:44
标题: pwm控制led亮度问题求助！！！
我用的是mc9s12xs128芯片，pwm占空比最开始设置的100%，通过定时器逐渐降低控制led亮度降低。
求大神帮忙看看哪里出错了，灯亮度没变，旁边的4位数码管还亮了。
#include <hidef.h>
#include "derivative.h"

#define LEDCPU PORTK_PK4
#define LEDCPU_dir DDRK_DDRK4
#define BUS_CLOCK    32000000
#define OSC_CLOCK    16000000
unsigned int p=100;

void INIT_PLL(void)//初始化锁相环
{
CLKSEL &= 0x7f;
PLLCTL &= 0x8F;
CRGINT &= 0xDF;
SYNR = 0x43;
REFDV = 0x81;
PLLCTL =PLLCTL|0x70;
asm NOP;
asm NOP;
while(!(CRGFLG&0x08));
CLKSEL |= 0x80;
}

void init_pwm(void)//初始化pwm
{
  PWMPOL_PPOL1= 1;
  PWMPRCLK = 0x22;
  PWMSCLA  =  0x04;
  PWMCLK =0x02;
  PWMCAE = 0x00;
  PWMPER1  = 100;
  PWMDTY1  = 100;
  PWME_PWME1 = 1;
}

void init_tim(void) //初始化定时器
{
  TSCR1_TFFCA = 1;
  TSCR1_TEN = 1;
  TIOS  = 0xff;
  TCTL1 = 0x00;
  TCTL2 = 0x00;
  TIE = 0x01;
  TSCR2 = 0x07;
  TFLG1 = 0xff;
  TFLG2 = 0xff;
}

void delay() //延时
{
  unsigned int i,j;
  for(i=0;i<2;i++)
  for(j=0;j<5000;j++);
}

#pragma CODE_SEG __NEAR_SEG NON_BANKED//计时中断
interrupt void scan(void)
{
  if(TFLG1_C0F == 1)
  {
TFLG1_C0F = 1;
TC0 = TCNT + 1250;
if(p>1) {
p--;
PWMDTY01=p;
}
else
p=100;
  }
}
#pragma CODE_SEG DEFAULT

void main(void)  //主函数
{
  DisableInterrupts;
  INIT_PLL();
  init_pwm();
  LEDCPU_dir=1;
  LEDCPU=0;
  EnableInterrupts;

  TFLG1_C0F = 1;
  TC0 = TCNT + 1250;
  for(;;){
  }
}

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