详解stm32的定时器8输出PWM

    我在定时器3的例程上面改，改了很久都没改好，百度看别人说定时器1和定时器8需要额外的指令用于PWM输出，今天下午硬件的人来要东西了，来不及研究了，于是网上找了个定时器8的4个通道全部可以输出的例程记录一下，已经经过本人试验是OK的。

1.调用：

 

TIM8_PWM_Init(1439 ,0);    //不分频。PWM频率=72000000/1440=50Khz

 

2.函数源码：

 

//TIM8 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 TIM8_PWM_Init(u16 arr,u16 psc)
{  
  GPIO_InitTypeDef GPIO_InitStructure;
  TIM_TimeBaseInitTypeDef  TIM_TimeBaseStructure;
  TIM_OCInitTypeDef  TIM_OCInitStructure;


  RCC_APB2PeriphClockCmd(RCC_APB2Periph_TIM8, ENABLE); //使能定时器3时钟
  RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOC, ENABLE);  //使能GPIO外设和AFIO复用功能模块时钟
  
  GPIO_InitStructure.GPIO_Pin = GPIO_Pin_6|GPIO_Pin_7|GPIO_Pin_8|GPIO_Pin_9; //TIM_CH2
  GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF_PP;  //复用推挽输出
  GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
  GPIO_Init(GPIOC, &GPIO_InitStructure);//初始化GPIO
  
  //初始化TIM8
  TIM_TimeBaseStructure.TIM_Period = arr; //设置在下一个更新事件装入活动的自动重装载寄存器周期的值
  TIM_TimeBaseStructure.TIM_Prescaler =psc; //设置用来作为TIMx时钟频率除数的预分频值
  TIM_TimeBaseStructure.TIM_ClockDivision = 0; //设置时钟分割:TDTS = Tck_tim
  TIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Up;  //TIM向上计数模式
  TIM_TimeBaseInit(TIM8, &TIM_TimeBaseStructure); //根据TIM_TimeBaseInitStruct中指定的参数初始化TIMx的时间基数单位


  //初始化TIM8 Channel2 PWM模式  
  TIM_OCInitStructure.TIM_OCMode = TIM_OCMode_PWM2; //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_OCIdleState = TIM_OCIdleState_Reset ;
  TIM_OCInitStructure.TIM_OCPolarity = TIM_OCPolarity_Low ; //输出极性:TIM输出比较极性高
  TIM_OC1Init(TIM8, &TIM_OCInitStructure);  //根据T指定的参数初始化外设TIM8 OC2


  TIM_OC1PreloadConfig(TIM8, TIM_OCPreload_Enable);  //使能TIM8在CCR2上的预装载寄存器


  TIM_SetCompare1(TIM8,474);


  TIM_OCInitStructure.TIM_OCMode = TIM_OCMode_PWM2; //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_OCIdleState = TIM_OCIdleState_Reset ;
  TIM_OCInitStructure.TIM_OCPolarity = TIM_OCPolarity_Low ; //输出极性:TIM输出比较极性高
  TIM_OC2Init(TIM8, &TIM_OCInitStructure);  //根据T指定的参数初始化外设TIM8 OC2


  TIM_OC2PreloadConfig(TIM8, TIM_OCPreload_Enable);  //使能TIM8在CCR2上的预装载寄存器


  TIM_SetCompare2(TIM8,700);


  TIM_OCInitStructure.TIM_OCMode = TIM_OCMode_PWM2; //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_OCIdleState = TIM_OCIdleState_Reset ;
  TIM_OCInitStructure.TIM_OCPolarity = TIM_OCPolarity_Low ; //输出极性:TIM输出比较极性高
  TIM_OC3Init(TIM8, &TIM_OCInitStructure);  //根据T指定的参数初始化外设TIM8 OC2


  TIM_OC3PreloadConfig(TIM8, TIM_OCPreload_Enable);  //使能TIM8在CCR2上的预装载寄存器


  TIM_SetCompare3(TIM8,900);


  TIM_OCInitStructure.TIM_OCMode = TIM_OCMode_PWM2; //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_OCIdleState = TIM_OCIdleState_Reset ;
  TIM_OCInitStructure.TIM_OCPolarity = TIM_OCPolarity_Low ; //输出极性:TIM输出比较极性高
  TIM_OC4Init(TIM8, &TIM_OCInitStructure);  //根据T指定的参数初始化外设TIM8 OC2


  TIM_OC4PreloadConfig(TIM8, TIM_OCPreload_Enable);  //使能TIM8在CCR2上的预装载寄存器


  TIM_SetCompare4(TIM8,1200);


  TIM_Cmd(TIM8, ENABLE);  //不使能TIM8


  TIM_CtrlPWMOutputs(TIM8,ENABLE);   
}

　　审核编辑：汤梓红