stm 通过 dam 控制pwm 占空比 代码

以下是基于STM32的代码，使用DMA控制PWM占空比：

1. 配置PWM模块

void PWM_Configuration(void)
{
  TIM_TimeBaseInitTypeDef TIM_TimeBaseStructure;
  TIM_OCInitTypeDef TIM_OCInitStructure;

  /* TIM clock enable */
  RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM4, ENABLE);

  /* Time base configuration */
  TIM_TimeBaseStructure.TIM_Period = 999; // PWM频率为1kHz
  TIM_TimeBaseStructure.TIM_Prescaler = 83; // 计数器时钟频率为84MHz/84=1MHz
  TIM_TimeBaseStructure.TIM_ClockDivision = 0;
  TIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Up;
  TIM_TimeBaseInit(TIM4, &TIM_TimeBaseStructure);

  /* PWM1 Mode configuration: Channel1 */
  TIM_OCInitStructure.TIM_OCMode = TIM_OCMode_PWM1;
  TIM_OCInitStructure.TIM_OutputState = TIM_OutputState_Enable;
  TIM_OCInitStructure.TIM_Pulse = 0; // 初始占空比为0
  TIM_OCInitStructure.TIM_OCPolarity = TIM_OCPolarity_High;
  TIM_OC1Init(TIM4, &TIM_OCInitStructure);

  TIM_OC1PreloadConfig(TIM4, TIM_OCPreload_Enable);

  /* TIM4 enable counter */
  TIM_Cmd(TIM4, ENABLE);
}

2. 配置DMA

void DMA_Configuration(void)
{
  DMA_InitTypeDef DMA_InitStructure;

  /* DMA clock enable */
  RCC_AHBPeriphClockCmd(RCC_AHBPeriph_DMA1, ENABLE);

  DMA_DeInit(DMA1_Channel1);

  DMA_InitStructure.DMA_PeripheralBaseAddr = (uint32_t) & (TIM4->CCR1);
  DMA_InitStructure.DMA_MemoryBaseAddr = (uint32_t) & g_pwm_duty;
  DMA_InitStructure.DMA_DIR = DMA_DIR_PeripheralDST;
  DMA_InitStructure.DMA_BufferSize = 1; // 传输数据大小为1字节
  DMA_InitStructure.DMA_PeripheralInc = DMA_PeripheralInc_Disable;
  DMA_InitStructure.DMA_MemoryInc = DMA_MemoryInc_Enable;
  DMA_InitStructure.DMA_PeripheralDataSize = DMA_PeripheralDataSize_Word;
  DMA_InitStructure.DMA_MemoryDataSize = DMA_MemoryDataSize_Byte;
  DMA_InitStructure.DMA_Mode = DMA_Mode_Circular;
  DMA_InitStructure.DMA_Priority = DMA_Priority_High;
  DMA_InitStructure.DMA_M2M = DMA_M2M_Disable;
  DMA_Init(DMA1_Channel1, &DMA_InitStructure);

  /* DMA1 Channel1 enable */
  DMA_Cmd(DMA1_Channel1, ENABLE);
}

3. 更新PWM占空比

void PWM_UpdateDuty(uint8_t duty)
{
  g_pwm_duty = duty;
}

在主程序中，可以通过调用`PWM_UpdateDuty`函数来更新PWM占空比，DMA会自动将数据传输到TIM4的CCR1寄存器中，从而实现PWM占空比的控制。