STM32 DAC+DMA实现正弦波输出，频率不可调

yyang0514 2015-10-20 05:47:29

现象：
无论如何修改TIM6的配置，通过示波器测量输出的波形始终为50Hz的正弦波。请问哪里出问题了。
关键代码如下：



#define DAC_DHR12R2_Address      0x40007414	 

const uint16_t Sine12bit[32] = {	  //数据源用来产生波形

                      2047, 2447, 2831, 3185, 3498, 3750, 3939, 4056, 4095, 4056,

                      3939, 3750, 3495, 3185, 2831, 2447, 2047, 1647, 1263, 909, 

                      599, 344, 155, 38, 0, 38, 155, 344, 599, 909, 1263, 1647};

uint32_t DualSine12bit[32];

uint32_t Idx = 0; 

int main(void)

{

   RCC_Configuration();	//系统时钟初始化

   GPIO_Configuration();//端口初始化    

   USART_Configuration();  

   for (Idx = 0; Idx < 32; Idx++)

   {

      //双通道输出正弦波

    DualSine12bit[Idx] = (Sine12bit[Idx] << 16) + (Sine12bit[Idx]);	 

   }

   DMA_Configuration();

   DAC_Configuration();

   /* Enable DMA for DAC Channel1 */

   DAC_DMACmd(DAC_Channel_1, ENABLE);

  /* TIM6 enable counter */

   TIM_Cmd(TIM6, ENABLE);

   while (1)

   {

   }   

}

void TIM_Configuration(void)

{

     TIM_TimeBaseInitTypeDef    TIM_TimeBaseStructure;

// 预计频率为2K

     TIM_TimeBaseStructInit(&TIM_TimeBaseStructure); 

     TIM_TimeBaseStructure.TIM_Period = 1000;       

     TIM_TimeBaseStructure.TIM_Prescaler = 35;   

     TIM_TimeBaseStructure.TIM_ClockDivision = 0x0;    

     TIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Up;  	

     TIM_TimeBaseInit(TIM6, &TIM_TimeBaseStructure);  

// TIM6 TRGO selection */

     TIM_SelectOutputTrigger(TIM6, TIM_TRGOSource_Update);	

}

void DAC_Configuration(void)

{

     DAC_InitTypeDef            DAC_InitStructure; 

    // DAC channel1 Configuration 

    //DAC触发  TIM6触发

     DAC_InitStructure.DAC_Trigger = DAC_Trigger_T6_TRGO;	 

     DAC_InitStructure.DAC_WaveGeneration = DAC_WaveGeneration_None;	 //不使用内部波形发生器

     DAC_InitStructure.DAC_OutputBuffer = DAC_OutputBuffer_Disable;   //关闭外部输出缓存

     //用DAC输出波形，传输的数据比较多，所以采用DMA传输可以节省CPU的开支

     DAC_Init(DAC_Channel_1, &DAC_InitStructure);

     DAC_Init(DAC_Channel_2, &DAC_InitStructure);

// Enable DAC Channel1: Once the DAC channel1 is enabled, PA.04 is automatically connected to the DAC converter

     DAC_Cmd(DAC_Channel_1, ENABLE);

     DAC_Cmd(DAC_Channel_2, ENABLE);

}

void DMA_Configuration(void)

{

      DMA_InitTypeDef            DMA_InitStructure;

      //将dma的通道寄存器设为默认值

      DMA_DeInit(DMA2_Channel4);	   

       //定义dma外设基地址 

      DMA_InitStructure.DMA_PeripheralBaseAddr = DAC_DHR12R2_Address;	 

      DMA_InitStructure.DMA_MemoryBaseAddr = (uint32_t)&Sine12bit;

       //外设作为数据传输的目的地 

      DMA_InitStructure.DMA_DIR = DMA_DIR_PeripheralDST;	

      DMA_InitStructure.DMA_BufferSize = 32;	  //dma缓存大小 

      //外设地址寄存器不变

      DMA_InitStructure.DMA_PeripheralInc = DMA_PeripheralInc_Disable;	

      //内存地址寄存器 递增

      DMA_InitStructure.DMA_MemoryInc = DMA_MemoryInc_Enable;	 

       //外设数据宽度 

      DMA_InitStructure.DMA_PeripheralDataSize = DMA_PeripheralDataSize_HalfWord;	

      DMA_InitStructure.DMA_MemoryDataSize = DMA_MemoryDataSize_HalfWord;

      //工作在循环缓存模式，数据传输数目为0时，自动恢复配置初值 

      DMA_InitStructure.DMA_Mode = DMA_Mode_Circular;	  

      DMA_InitStructure.DMA_Priority = DMA_Priority_High;

      //通道未被设置成内存到内存模式，与循环模式相对

      DMA_InitStructure.DMA_M2M = DMA_M2M_Disable;

       //将DMA_InitStructure中指定的参数初始化dma的通道寄存器 	 

      DMA_Init(DMA2_Channel4, &DMA_InitStructure);	 

     // Enable DMA2 Channel4 

      DMA_Cmd(DMA2_Channel4, ENABLE);	 

}