DAC输出用定时器触发，程序运行后怎么再修改DAC发送时间间隔

huaxiang123 · 发表于 2019-8-21 17:28:11

DAC初始化程序
void DAC_Config(void)
{
GPIO_InitTypeDef  GPIO_InitStructure;
DAC_InitTypeDef DAC_InitStructure;
#if DAC2_DMA == 1
      DMA_InitTypeDef  DMA_InitStructure;
#endif
RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOA,ENABLE); //使能GPIOA
RCC_APB1PeriphClockCmd(RCC_APB1Periph_DAC,ENABLE);    //使能DAC时钟
#if DAC2_DMA == 1
      RCC_AHBPeriphClockCmd(RCC_AHBPeriph_DMA2,ENABLE);
#endif

GPIO_InitStructure.GPIO_Pin = GPIO_Pin_5;
GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AIN;
GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
GPIO_Init(GPIOA,&GPIO_InitStructure);
//DAC_InitStructure.DAC_Trigger = DAC_Trigger_None; //不使用触发功能
DAC_InitStructure.DAC_Trigger = DAC_Trigger_T2_TRGO;    //使用TIM2作为触发源
DAC_InitStructure.DAC_WaveGeneration = DAC_WaveGeneration_None;  //不使用波形发生器
DAC_InitStructure.DAC_LFSRUnmask_TriangleAmplitude = DAC_LFSRUnmask_Bit0;  //屏蔽、幅值设置
DAC_InitStructure.DAC_OutputBuffer = DAC_OutputBuffer_Disable; //不使用DAC输出缓冲
DAC_Init(DAC_Channel_2,&DAC_InitStructure);
DAC_Cmd(DAC_Channel_2,ENABLE); //使能DAC2 由PA5输出
DAC_SetChannel2Data(DAC_Align_12b_R,0); //12位右对齐数据格式设置DAC值，刚开始为0
DAC_DMACmd(DAC_Channel_2,ENABLE); //使能DAC的DMA请求
#if DAC2_DMA == 1
      DMA_DeInit(DMA2_Channel4);
      DMA_InitStructure.DMA_PeripheralBaseAddr = (u32)&DAC->DHR12R2;          //DMA外设基地址 DHR12R2

AC2的12位右对齐数据地址
      DMA_InitStructure.DMA_MemoryBaseAddr    = (u32)DAC2_buffer;             //DMA内存基地址
      DMA_InitStructure.DMA_DIR             = DMA_DIR_PeripheralDST;       //数据传输方向，从内存读取发送到外设
      DMA_InitStructure.DMA_BufferSize       = DAC2_SIZE;                   //DMA通道的DMA缓存的大小
      DMA_InitStructure.DMA_PeripheralInc    = DMA_PeripheralInc_Disable;    //外设地址寄存器不变
      DMA_InitStructure.DMA_MemoryInc       = DMA_MemoryInc_Enable;          //内存地址寄存器递增
      DMA_InitStructure.DMA_PeripheralDataSize = DMA_PeripheralDataSize_HalfWord;//外设数据宽度为16位
      DMA_InitStructure.DMA_MemoryDataSize    = DMA_MemoryDataSize_HalfWord; //内存数据宽度为16位
      DMA_InitStructure.DMA_Mode             = DMA_Mode_Normal;             //工作在正常模式
//DMA_InitStructure.DMA_Mode             = DMA_Mode_Circular;             //循环模式
      DMA_InitStructure.DMA_Priority          = DMA_Priority_Medium;          //DMA通道 x拥有中优先级
      DMA_InitStructure.DMA_M2M             = DMA_M2M_Disable;             //DMA通道x没有设置为内存到内存传输
      DMA_Init(DMA2_Channel4, &DMA_InitStructure);

      TIM2_Config(DAC2_TIME-1,71);                                           //10*72/72000000=10us传传输一个点

      //DMA_Cmd(DMA2_Channel4, ENABLE);                                           //使能通道,开启一次DMA传输
DMA_Cmd(DMA2_Channel4, DISABLE);
#endif
}

定时器程序
void TIM2_Config(unsigned short int arr,unsigned short int psc)
{
  TIM_TimeBaseInitTypeDef  TIM_TimeBaseStructure;

  RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM2, ENABLE);       //时钟使能

  //定时器TIM2初始化
  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 = TIM_CKD_DIV1;    //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(TIM2, &TIM_TimeBaseStructure);          //根据指定的参数初始化TIMx的时间基数单位
//TIM_ITConfig(TIM2,TIM_DIER_UDE,ENABLE);                   //TIM_DIER_UDE：更新DMA请求使能
/* 配置TIM2触发源 */
  TIM_SelectOutputTrigger(TIM2, TIM_TRGOSource_Update);

  TIM_Cmd(TIM2, ENABLE);                                     //使能TIMx
}