stm32 pwm频率与周期计算

频率

Fpwm = 100M / ((arr+1)*(psc+1))(单位：Hz)

arr 是计数值

psc 是预分频值

如：

3. 主频=100M

4. arr=100

5. psc=1000

100,000,000/100/1000=1000Hz

占空比

duty circle = TIM3->CCR1 / arr(单位：%)

TIM3->CCR1 是捕获比较寄存器值

从下面代码可以看出TIM3->CCR1 就是对应的sConfigOC.Pulse

arr对应htim5.Init.Period = 999;

psc对应htim5.Init.Prescaler = 99;

如果 arr=1000,TIM3->CCR1=500则pwm的占空比为50%，通过修改CCR1可以修改占空比，修改arr可以修改频率

/* TIM5 init function */

void MX_TIM5_Init(void)

{

  TIM_MasterConfigTypeDef sMasterConfig = {0};

  TIM_OC_InitTypeDef sConfigOC = {0};

  htim5.Instance = TIM5;

  htim5.Init.Prescaler = 99;

  htim5.Init.CounterMode = TIM_COUNTERMODE_UP;

  htim5.Init.Period = 999;

  htim5.Init.ClockDivision = TIM_CLOCKDIVISION_DIV1;

  if (HAL_TIM_PWM_Init(&htim5) != HAL_OK)

  {

    Error_Handler();

  }

  sMasterConfig.MasterOutputTrigger = TIM_TRGO_RESET;

  sMasterConfig.MasterSlaveMode = TIM_MASTERSLAVEMODE_DISABLE;

  if (HAL_TIMEx_MasterConfigSynchronization(&htim5, &sMasterConfig) != HAL_OK)

  {

    Error_Handler();

  }

  sConfigOC.OCMode = TIM_OCMODE_PWM1;

  sConfigOC.Pulse = 0;

  sConfigOC.OCPolarity = TIM_OCPOLARITY_HIGH;

  sConfigOC.OCFastMode = TIM_OCFAST_DISABLE;

  if (HAL_TIM_PWM_ConfigChannel(&htim5, &sConfigOC, TIM_CHANNEL_2) != HAL_OK)

  {

    Error_Handler();

  }

  HAL_TIM_MspPostInit(&htim5);

}

static void TIM_OC1_SetConfig(TIM_TypeDef *TIMx, TIM_OC_InitTypeDef *OC_Config){

...

/* Set the Capture Compare Register value */

  TIMx->CCR1 = OC_Config->Pulse;

}