通用定时器输出PWM波

只看该作者 · 2019-11-28 18:54

在输出PWM波时，有一部分代码没看懂，查了好多资料也没有弄明白，在stm固件库里面提供的函数中没有找到下面红色标注的部分，而且不明白（ TIM_OCInitStructure.TIM_OutputState = TIM_OutputState_Enable;）这句代码的意思，求大神指教？

static void TIM3_Mode_Config(void)

{

      TIM_TimeBaseInitTypeDef  TIM_TimeBaseStructure;

      TIM_OCInitTypeDef  TIM_OCInitStructure;

      /* PWM信号电平跳变值 */

      u16 CCR1_Val = 500;

      u16 CCR2_Val = 375;

      u16 CCR3_Val = 250;

      u16 CCR4_Val = 125;

/* -----------------------------------------------------------------------

TIM3 Channel1 duty cycle = (TIM3_CCR1/ TIM3_ARR+1)* 100% = 50%

TIM3 Channel2 duty cycle = (TIM3_CCR2/ TIM3_ARR+1)* 100% = 37.5%

TIM3 Channel3 duty cycle = (TIM3_CCR3/ TIM3_ARR+1)* 100% = 25%

TIM3 Channel4 duty cycle = (TIM3_CCR4/ TIM3_ARR+1)* 100% = 12.5%

  ----------------------------------------------------------------------- */

  /* Time base configuration */

  TIM_TimeBaseStructure.TIM_Period = 999;    //当定时器从0计数到999，即为1000次，为一个定时周期

  TIM_TimeBaseStructure.TIM_Prescaler = 0;          //设置预分频：不预分频，即为72MHz

  TIM_TimeBaseStructure.TIM_ClockDivision = TIM_CKD_DIV1 ;       //设置时钟分频系数：不分频(这里用不到)

  TIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Up;  //向上计数模式

  TIM_TimeBaseInit(TIM3, &TIM_TimeBaseStructure);

  /* PWM1 Mode configuration: Channel1 */

  TIM_OCInitStructure.TIM_OCMode = TIM_OCMode_PWM1;          //配置为PWM模式1

TIM_OCInitStructure.TIM_OutputState = TIM_OutputState_Enable;

  TIM_OCInitStructure.TIM_Pulse = CCR1_Val;          //设置跳变值，当计数器计数到这个值时，电平发生跳变

  TIM_OCInitStructure.TIM_OCPolarity = TIM_OCPolarity_High;  //当定时器计数值小于CCR1_Val时为高电平

TIM_OC1Init(TIM3, &TIM_OCInitStructure);       //使能通道1

  TIM_OC1PreloadConfig(TIM3, TIM_OCPreload_Enable);

  /* PWM1 Mode configuration: Channel2 */

TIM_OCInitStructure.TIM_OutputState = TIM_OutputState_Enable;

  TIM_OCInitStructure.TIM_Pulse = CCR2_Val;       //设置通道2的电平跳变值，输出另外一个占空比的PWM

  TIM_OC2Init(TIM3, &TIM_OCInitStructure);       //使能通道2

  TIM_OC2PreloadConfig(TIM3, TIM_OCPreload_Enable);

  /* PWM1 Mode configuration: Channel3 */

  TIM_OCInitStructure.TIM_OutputState = TIM_OutputState_Enable;

  TIM_OCInitStructure.TIM_Pulse = CCR3_Val;       //设置通道3的电平跳变值，输出另外一个占空比的PWM

  TIM_OC3Init(TIM3, &TIM_OCInitStructure);       //使能通道3

  TIM_OC3PreloadConfig(TIM3, TIM_OCPreload_Enable);

  /* PWM1 Mode configuration: Channel4 */

  TIM_OCInitStructure.TIM_OutputState = TIM_OutputState_Enable;

  TIM_OCInitStructure.TIM_Pulse = CCR4_Val;       //设置通道4的电平跳变值，输出另外一个占空比的PWM

  TIM_OC4Init(TIM3, &TIM_OCInitStructure);       //使能通道4

  TIM_OC4PreloadConfig(TIM3, TIM_OCPreload_Enable);

  TIM_ARRPreloadConfig(TIM3, ENABLE);                      // 使能TIM3重载寄存器ARR

  /* TIM3 enable counter */

  TIM_Cmd(TIM3, ENABLE);                //使能定时器3

}

通用定时器输出PWM波

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