求助为啥我用定时器的比较模式频率改变不了改自动重装载值频率不变

stm32sport · 发表于 2017-9-21 10:33:14

我这边想用stm32的定时器3控制步进电机驱动器发送脉冲。用输出比较模式能输出脉冲。但是发现改变重装载值频率不变。不知道什么问题希望大家回答下。谢谢了。
工程文件我发布在下面了。大家可以看看。
#include "sys.h"
#include "timer.h"
#include "led.h"
void timer3_PWM_init(void)
{
GPIO_InitTypeDef GPIO_InitStructure;
NVIC_InitTypeDef NVIC_InitStructure;
TIM_TimeBaseInitTypeDef TIM_TimeBaseStructure;
TIM_OCInitTypeDef TIM_OCInitStructure;

RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM3, ENABLE);
RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOB, ENABLE);
//Step1. PB.1口设置为TIM3的OC4输出口
GPIO_InitStructure.GPIO_Pin = GPIO_Pin_1;
GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF_PP;
GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
GPIO_Init(GPIOB, &GPIO_InitStructure);
//Step3.使能TIM3的输出比较匹配中断
NVIC_InitStructure.NVIC_IRQChannel = TIM3_IRQn;
NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 1;
NVIC_InitStructure.NVIC_IRQChannelSubPriority = 1;
NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;
NVIC_Init(&NVIC_InitStructure);

TIM_TimeBaseStructure.TIM_Prescaler = 71;       //分频系数为71  得到真正的时基单元为72M/（71+1）=1M
TIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Up;       //向上计数
TIM_TimeBaseStructure.TIM_Period = 0xffff; //自装载值为65535  特殊值
TIM_TimeBaseStructure.TIM_ClockDivision = 0;
TIM_TimeBaseInit(TIM3,&TIM_TimeBaseStructure);

/* Channel 4 Configuration in oc mode */
TIM_OCStructInit(&TIM_OCInitStructure);
TIM_OCInitStructure.TIM_OCMode = TIM_OCMode_Toggle;       //触发事件电平翻转
TIM_OCInitStructure.TIM_OutputState = TIM_OutputState_Enable;          //开启输出
TIM_OCInitStructure.TIM_Pulse = 10000;          //10000
TIM_OCInitStructure.TIM_OCPolarity = TIM_OCPolarity_High;       //输出极性

TIM_OC4Init(TIM3,&TIM_OCInitStructure);       //通道4
TIM_ClearFlag(TIM3, TIM_FLAG_CC1|TIM_FLAG_CC2|TIM_FLAG_CC3|TIM_FLAG_CC4);//清中断标志位
TIM_ITConfig(TIM3, TIM_IT_CC4, ENABLE);//TIM3中断源设置，开启相应通道的捕捉比较中断

TIM_Cmd(TIM3, ENABLE);

//TIM_OC4PreloadConfig(TIM3,TIM_OCPreload_Enable);//使能定时器2的通道1预装载寄存器
}

void TIM3_IRQHandler(void)
{
   int capture;
   u16 led0pwmval=0;
   u8 dir=1;
   if(TIM_GetITStatus(TIM3,TIM_IT_CC4) == SET)
   {
   if(dir)led0pwmval++;
   else led0pwmval--;
   if(led0pwmval>3000)dir=0;
   if(led0pwmval==0)dir=1;
      TIM_ClearITPendingBit(TIM3, TIM_IT_CC4 );
      capture = TIM_GetCapture1(TIM3);
      TIM_SetCompare4(TIM3, capture + led0pwmval);

   }
}