求助,关于pwm发送脉冲问题

真物 · 发表于 2021-1-26 22:21:25

我看了原子哥的pwm输出实验后，结合网上的一些资料，在stm32f407zgt6的芯片上做了一个能输出1HZ——1MHZ的程序，然后想要移植到stm32f407igt6芯片上，那个板子的晶振好像是12mhz的，然后输出现象是我的程序要输出1HZ的波形变成了1.5HZ的波形。然后我看百度说要改system_sm32f4xx.c  文件，将  #define HSE_BYPASS_INPUT_FREQUENCY 8000000改为了12000000，结果是程序是输出1HZ了，可是上线的1MHZ到不了了。改了半天也没成功，我试了半天好像只能达到800kHZ左右。有没有大佬知道这该怎么解决。代码如下:
#include "pwm.h"
#include "led.h"
#include "usart.h"

//TIM14 PWM部分初始化
//PWM输出初始化
//arr：自动重装值
//psc：时钟预分频数
void TIM14_PWM_Init()
{
//此部分需手动修改IO口设置
  uint32_t temp32;
  uint32_t uhTimerfrequency;
  uint16_t uhTimerPeriod;
  uint16_t uhTimerPulse;
GPIO_InitTypeDef GPIO_InitStructure;
TIM_TimeBaseInitTypeDef  TIM_TimeBaseStructure;
TIM_OCInitTypeDef  TIM_OCInitStructure;

RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM14,ENABLE);    //TIM14时钟使能
RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_GPIOF, ENABLE); //使能PORTF时钟

GPIO_PinAFConfig(GPIOF,GPIO_PinSource9,GPIO_AF_TIM14); //GPIOA7复用为定时器14

GPIO_InitStructure.GPIO_Pin = GPIO_Pin_9;          //GPIOA7
GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF;       //复用功能
GPIO_InitStructure.GPIO_Speed = GPIO_Speed_100MHz; //速度100MHz
GPIO_InitStructure.GPIO_OType = GPIO_OType_PP;    //推挽复用输出
GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_UP;       //上拉
GPIO_Init(GPIOF,&GPIO_InitStructure);             //初始化PA7

uhTimerfrequency = 200000;
temp32 = ((SystemCoreClock / 2) / uhTimerfrequency);
  if (temp32 > 65535)
temp32 = 65535;
  uhTimerPeriod = (uint16_t) temp32;
  uhTimerPulse  = uhTimerPeriod * 50 / 100;
TIM_TimeBaseStructure.TIM_Prescaler=0;  //定时器分频
TIM_TimeBaseStructure.TIM_CounterMode=TIM_CounterMode_Up; //向上计数模式
TIM_TimeBaseStructure.TIM_Period=uhTimerPeriod-1; //自动重装载值
TIM_TimeBaseStructure.TIM_ClockDivision=TIM_CKD_DIV1;

TIM_TimeBaseInit(TIM14,&TIM_TimeBaseStructure);//初始化定时器14

//初始化TIM14 Channel1 PWM模式
TIM_OCInitStructure.TIM_OCMode = TIM_OCMode_PWM1; //选择定时器模式:TIM脉冲宽度调制模式2
TIM_OCInitStructure.TIM_OutputState = TIM_OutputState_Enable; //比较输出使能
TIM_OCInitStructure.TIM_OCPolarity = TIM_OCPolarity_Low; //输出极性:TIM输出比较极性低
TIM_OC1Init(TIM14, &TIM_OCInitStructure);  //根据T指定的参数初始化外设TIM1 4OC1

TIM_OC1PreloadConfig(TIM14, TIM_OCPreload_Enable);  //使能TIM14在CCR1上的预装载寄存器

  TIM_ARRPreloadConfig(TIM14,ENABLE);//ARPE使能

TIM_Cmd(TIM14, ENABLE);  //使能TIM14


}

void StdPeriph_TIM14_PWM_Update(uint32_t TIM14_PWM_FQ,uint32_t TIM14_PWM_Pulse)
{
   uint32_t TIM14_PWM_FQ_Old  = 0;
   uint32_t TIM14_PWM_Pulse_Old = 0;
uint32_t temp32;
uint32_t uhTimerfrequency;
uint32_t uhTimerPeriod;
uint32_t uhTimerPrescaler;
uint32_t uhTimerPulse;
if ((TIM14_PWM_FQ_Old != TIM14_PWM_FQ) || (TIM14_PWM_Pulse_Old != TIM14_PWM_Pulse))
{
      TIM14_PWM_FQ_Old  =  TIM14_PWM_FQ;
      TIM14_PWM_Pulse_Old = TIM14_PWM_Pulse;
      if (TIM14_PWM_FQ >= 4000) {
         uhTimerfrequency = TIM14_PWM_FQ;  /* 定时器计时频率和PWM频率相等 */
         uhTimerPrescaler = 1; /* 实际频率TIM14_PWM_FQ较大时，TIM14设置分频为1(不分频) */
      } else {
         uhTimerfrequency = 4000; /* 实际频率TIM14_PWM_FQ较小时，和4000Hz的频率比较，看相差几倍 */
         uhTimerPrescaler = 4000 / TIM14_PWM_FQ;  /* 实际频率和4000相差的倍数作为TIM2的分频设置值 */
         uhTimerfrequency = uhTimerPrescaler * TIM14_PWM_FQ; /* TIM14分频后，计时周期变长，需要将uhTimerfrequency倍频  */
      }

      /* TIM14的周期要通过倍频uhTimerfrequency来计算,uhTimerPeriod = 84MHz / uhTimerfrequency */
      temp32 = ((SystemCoreClock / 2) / uhTimerfrequency);
      if (temp32 > 65535) temp32 = 65535;
      uhTimerPeriod = (uint16_t) temp32;

      if (TIM14_PWM_Pulse > 100) TIM14_PWM_Pulse = 100;
      uhTimerPulse = uhTimerPeriod * TIM14_PWM_Pulse / 100;

      TIM14->ARR  = uhTimerPeriod - 1;
      TIM14->PSC  = uhTimerPrescaler - 1;
      TIM14->CCR1 = uhTimerPulse;
      TIM14->EGR  = TIM_PSCReloadMode_Update;
}
}