Timer2产生PWM，变频一会后CNT值不重载

cs1222 · 发表于 2017-5-27 10:49:33

今遇到一个问题，希望用Timer产生PWM波，驱动步进电机加减速，用到了Timer1/2/3/4/8。但是Timer2加减速一会后CNT一直累加不清零。其他定时器均正常；
Timer2定时器配置如下：
void Timer2_CH2_GPIO_Init(void)
{
  GPIO_InitTypeDef GPIO_InitStructure;

  GPIO_InitStructure.GPIO_Pin=GPIO_Pin_1;
  GPIO_InitStructure.GPIO_Mode=GPIO_Mode_AF;
  GPIO_InitStructure.GPIO_Speed=GPIO_Speed_100MHz;
  GPIO_InitStructure.GPIO_OType = GPIO_OType_PP;
  GPIO_InitStructure.GPIO_PuPd=GPIO_PuPd_UP;
  GPIO_Init(GPIOA,&GPIO_InitStructure);

  GPIO_PinAFConfig(GPIOA,GPIO_PinSource1,GPIO_AF_TIM2);
}

void Timer2_CH2_Config(u32 Prescaler,u32 Period,u32 duty_cycle)
{
  TIM_TimeBaseInitTypeDef  TIM_TimeBaseStructure;
  TIM_OCInitTypeDef TIM_OCInitStructure1;

  /* TIM2 Periph clock enable */
  RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM2, ENABLE); //使能TIM2时钟 84MHZ

  /* 分频和周期计算公式：Prescaler = (TIMxCLK/TIMx counter clock)-1

eriod=(TIMx counter clock/
  TIMx output clock)-1 TIMx counter clock为你所需要的TIMx的定时器时钟*/
  TIM_TimeBaseStructure.TIM_Prescaler = Prescaler-1;    // 设置预分频：84，即为 1MHz
  TIM_TimeBaseStructure.TIM_Period = Period-1;
  TIM_TimeBaseStructure.TIM_ClockDivision = TIM_CKD_DIV1; //TIM_CKD_DIV1=0x0;
  TIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Up;
  TIM_TimeBaseInit(TIM2, &TIM_TimeBaseStructure);

  TIM_OCInitStructure1.TIM_OCMode = TIM_OCMode_PWM1;//PWM1为正常占空比模式，PWM2为反极性模式
  TIM_OCInitStructure1.TIM_OutputState = TIM_OutputState_Enable;//使能输出状态
  TIM_OCInitStructure1.TIM_Pulse = duty_cycle;//占空比
  TIM_OCInitStructure1.TIM_OCPolarity = TIM_OCPolarity_High;//High为占空比高极性，此时占空比为20%；Low则为反极性，占空比为80%

  TIM_OC2Init(TIM2, &TIM_OCInitStructure1);//OC1初始化
}

步进电机驱动芯片为DRV8825根据PWM频率不同，速度不同；
程序中采用TIM_SetAutoreload(TIM2,***)来改变PWM频率。
微信图片_20170527104637.png