求助大佬们，PWM调节频率保持占空比不变

WTC960522

大佬们，有没有什么办法做到PWM输出在改变频率的同时保持占空比不会变化
这是我写的函数，在CCR的值较小的时候调节频率占空比就变了。
int main(void)

{
  u16 pa6pwmval=144;
u32 b=250000;
u16 z;
  u16 d;
  u8 key;
u16 a=288;
delay_init();       //ÑÓʱº¯Êý³õʼ»¯   
NVIC_PriorityGroupConfig(NVIC_PriorityGroup_2);   //ÉèÖÃNVICÖжϷÖ×é2:2λÇÀÕ¼ÓÅÏȼ¶£¬2λÏìÓ¦ÓÅÏȼ¶
  KEY_Init();      //KEY³õʼ»¯
OUT_init();
TIM4_PWM_Init(a-1,0); //TIM4 PWM³õʼ»¯, Fpwm=72M/256=281.25Khz.
  TIM_SetCompare4(TIM4,pa6pwmval);//³õʼֵΪ0
while(1)
{
   
key=KEY_Scan(1);

  if(key==KEY1_PRES)
  {   
   if(pa6pwmval<(a+1))pa6pwmval+=10;
   TIM_SetCompare4(TIM4,pa6pwmval);   
  }else if(key==KEY2_PRES)
  {
   if(pa6pwmval>10)pa6pwmval-=10;
   else pa6pwmval=0;
   TIM_SetCompare4(TIM4,pa6pwmval);   
  }else if(key==KEY3_PRES)
  {z=a/pa6pwmval;
   
   if(b<300000)b+=1000;
  a=72000000/b;
   pa6pwmval=a/z;
   
   TIM4_PWM_Init(a-1,0);
   
   TIM_SetCompare4(TIM4,pa6pwmval);
      
  }  else if(key==KEY4_PRES)
  {z=a/pa6pwmval;

   if(b>200000)b-=1000;
  a=72000000/b;
   pa6pwmval=a/z;
   
   TIM4_PWM_Init(a-1,0);
   
   TIM_SetCompare4(TIM4,pa6pwmval);   
  }   
delay_ms(50);
  
  
  

}

}

WTC960522

已经做出来了，虽然不是太完美，改变了计算的方法
#include "sys.h"
#include "o.h"
#include "t.h"
#include "delay.h"
#include "k.h"
#include "sys.h"

int main(void)
{
  float pa6pwmval=144;
u32 b=250000;
u16 z=50;
  u8 key;
float a=288;
delay_init();       //&Ntilde;&Oacute;&Ecirc;±&ordm;&macr;&Ecirc;&yacute;&sup3;&otilde;&Ecirc;&frac14;&raquo;&macr;   
NVIC_PriorityGroupConfig(NVIC_PriorityGroup_2);   //&Eacute;è&Ouml;&Atilde;NVIC&Ouml;&ETH;&para;&Iuml;·&Ouml;×é2:2&Icirc;&raquo;&Ccedil;&Agrave;&Otilde;&frac14;&Oacute;&Aring;&Iuml;&Egrave;&frac14;&para;&pound;&not;2&Icirc;&raquo;&Iuml;ì&Oacute;&brvbar;&Oacute;&Aring;&Iuml;&Egrave;&frac14;&para;
  KEY_Init();      //KEY&sup3;&otilde;&Ecirc;&frac14;&raquo;&macr;
OUT_init();
TIM4_PWM_Init(a-1,0); //TIM4 PWM&sup3;&otilde;&Ecirc;&frac14;&raquo;&macr;, Fpwm=72M/256=281.25Khz.
  TIM_SetCompare4(TIM4,pa6pwmval);//&sup3;&otilde;&Ecirc;&frac14;&Ouml;&micro;&Icirc;&ordf;0


while(1)
{
  
key=KEY_Scan(1);

  if(key==KEY1_PRES)
  {  if(z<100)z+=1;
        pa6pwmval=a*z/100;   
   
   TIM_SetCompare4(TIM4,pa6pwmval);   
  }else if(key==KEY2_PRES)
  {
   if(z>0)z-=1;
   pa6pwmval=a*z/100;
   
   TIM_SetCompare4(TIM4,pa6pwmval);   
  }else if(key==KEY3_PRES)
  {
   
   if(b<300000)b+=1000;
  a=72000000/b;
   pa6pwmval=a*z/100;
   
   TIM4_PWM_Init(a-1,0);
   
   TIM_SetCompare4(TIM4,pa6pwmval);
      
  }  else if(key==KEY4_PRES)
  {
   if(b>200000)b-=1000;
  a=72000000/b;
   pa6pwmval=a*z/100;
   
   TIM4_PWM_Init(a-1,0);
   
   TIM_SetCompare4(TIM4,pa6pwmval);   
  }  else if(key==KEY5_PRES)
{
}  
delay_ms(50);
  
  
  

}

}

WTC960522

木有大佬在的吗？好难过

张彦雷

你修改预分频的值就行了

sakura87999

配置成为比较翻转输出可以很方便改变频率