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正弦波关键代码：(DAC用的是单通道)

TIM_InitStruct.TIM_Period = 0x19;
 TIM_InitStruct.TIM_Prescaler = 0x0;
 TIM_InitStruct.TIM_ClockDivision = 0x0;
 TIM_InitStruct.TIM_CounterMode = TIM_CounterMode_Up;

 TIM_TimeBaseInit(TIM2 , &TIM_InitStruct);
 /*TIM_PrescalerConfig(TIM6, 0xF, TIM_PSCReloadMode_Update);
   TIM_SetAutoreload(TIM6, 0xFF);
    TIM6 TRGO selection */
   //TIM_SelectOutputTrigger(TIM6, TIM_TRGOSource_Update);

 TIM_SelectOutputTrigger(TIM2 , TIM_TRGOSource_Update);

 /* DAC 构造 */
 DAC_InitStruct.DAC_Trigger = DAC_Trigger_T2_TRGO;
 DAC_InitStruct.DAC_WaveGeneration = DAC_WaveGeneration_None;
 DAC_InitStruct.DAC_LFSRUnmask_TriangleAmplitude = DAC_TriangleAmplitude_2047;
 DAC_InitStruct.DAC_OutputBuffer = DAC_OutputBuffer_Disable;

 DAC_Init(DAC_Channel_1 , &DAC_InitStruct);

 for(Idx=0;Idx<256;Idx++)
 {
  SigSine12bit[Idx] = (0xffff0000 << 16) + (Sine12bit[Idx]);
 }/**/

 /* DMA 构造 */
 DMA_InitStruct.DMA_PeripheralBaseAddr = 0x40007408;
 DMA_InitStruct.DMA_MemoryBaseAddr = (uint32_t)&SigSine12bit;
 DMA_InitStruct.DMA_DIR = DMA_DIR_PeripheralDST;
 DMA_InitStruct.DMA_BufferSize = 256;
 DMA_InitStruct.DMA_PeripheralInc = DMA_PeripheralInc_Disable;
 DMA_InitStruct.DMA_MemoryInc = DMA_MemoryInc_Enable;
 DMA_InitStruct.DMA_PeripheralDataSize = DMA_PeripheralDataSize_Word;
 DMA_InitStruct.DMA_MemoryDataSize = DMA_MemoryDataSize_Word;
 DMA_InitStruct.DMA_Mode = DMA_Mode_Circular;
 DMA_InitStruct.DMA_Priority = DMA_Priority_High;
 DMA_InitStruct.DMA_M2M = DMA_M2M_Disable;

 DMA_Init(DMA2_Channel3 , &DMA_InitStruct);//要用DMA2

 DMA_Cmd(DMA2_Channel3 , ENABLE);//使能DMA2

 DAC_Cmd(DAC_Channel_1 , ENABLE);//使能DAC通道1
 DAC_DMACmd(DAC_Channel_1 , ENABLE);

 TIM_Cmd(TIM2 , ENABLE);

 三角波关键代码：

 TIM_InitStruct.TIM_Period = 0x19;
 TIM_InitStruct.TIM_Prescaler = 0x0;
 TIM_InitStruct.TIM_ClockDivision = 0x0;
 TIM_InitStruct.TIM_CounterMode = TIM_CounterMode_Up;
 TIM_TimeBaseInit(TIM2 , &TIM_InitStruct);

 TIM_SelectOutputTrigger(TIM2, TIM_TRGOSource_Update);

/* Set GPIO_DAC */
 GPIOA_InitStruct.GPIO_Pin = GPIO_Pin_4;
 GPIOA_InitStruct.GPIO_Speed = GPIO_Speed_50MHz;
 GPIOA_InitStruct.GPIO_Mode = GPIO_Mode_AIN;

 GPIO_Init(DAC_GPIOA , &GPIOA_InitStruct);

/* Set DAC */
 //DAC_Cmd(DAC_Channel_1,ENABLE);

 DAC_InitStruct.DAC_Trigger = DAC_Trigger_T2_TRGO;
 DAC_InitStruct.DAC_LFSRUnmask_TriangleAmplitude = DAC_TriangleAmplitude_2047;
 DAC_InitStruct.DAC_OutputBuffer = DAC_OutputBuffer_Disable;
 DAC_InitStruct.DAC_WaveGeneration = DAC_WaveGeneration_Triangle;//三角波触发方式

 DAC_Init(DAC_Channel_1 , &DAC_InitStruct);

 DAC_Cmd(DAC_Channel_1, ENABLE);//使能DAC通道1

 DAC_SetChannel1Data(DAC_Align_12b_R , 0x000);

 TIM_Cmd(TIM2 , ENABLE);

谢谢你的鼓励~

TIM定时器的定时时间计算：
摘自百度文库（可能有点模糊，海涵啦~）

定时器定时和中断先附上代码（没有相机，要找别人借，这得天天麻烦别人囧）
/* 结构体 */
 TIM_TimeBaseInitTypeDef TIM_BaseInitStruct;
 NVIC_InitTypeDef NVIC_InitStruct;
 //TIM_OCInitTypeDef TIM_OCInitStruct;

 /* 构造基本定时单元TIM2 */
 TIM_BaseInitStruct.TIM_Prescaler = 9999;
 TIM_BaseInitStruct.TIM_Period = 7199;
 TIM_BaseInitStruct.TIM_CounterMode = TIM_CounterMode_Up;
 TIM_BaseInitStruct.TIM_ClockDivision = 0x0;
 TIM_TimeBaseInit(TIM2 , &TIM_BaseInitStruct);

 /*TIM_OCInitStruct.TIM_OCMode = TIM_OCMode_Timing;
 TIM_OCInitStruct.TIM_OutputState = TIM_OutputState_Enable;
 TIM_OCInitStruct.TIM_OutputNState = TIM_OutputNState_Enable;
 TIM_OCInitStruct.TIM_Pulse = 0x0;
 TIM_OCInitStruct.TIM_OCPolarity = TIM_OCPolarity_Low;
 TIM_OCInitStruct.TIM_OCNPolarity = TIM_OCNPolarity_High;
 TIM_OCInitStruct.TIM_OCIdleState = TIM_OCIdleState_Set;
 TIM_OCInitStruct.TIM_OCNIdleState = TIM_OCIdleState_Reset;
 TIM_OC1Init(TIM2 , &TIM_OCInitStruct);*/

 /* 构造嵌套向量中断控制 */
 NVIC_PriorityGroupConfig(NVIC_PriorityGroup_1);
 NVIC_InitStruct.NVIC_IRQChannel = TIM2_IRQn;
 NVIC_InitStruct.NVIC_IRQChannelPreemptionPriority = 0;
 NVIC_InitStruct.NVIC_IRQChannelSubPriority = 4;
 NVIC_InitStruct.NVIC_IRQChannelCmd = ENABLE;
 NVIC_Init(&NVIC_InitStruct);

 /* 开启时钟中断 */
 TIM_ITConfig(TIM2 , TIM_IT_Update , ENABLE);
 
 /* 使能定时器2 */
 TIM_Cmd(TIM2 , ENABLE);

自己手上的固件库使用手册不是最新版的，而固件库是最新版的，不搭！结果悲剧，NVIC让我搞半天，NVIC头文件是misc.h旧版的却是stm32f10x_nvic.h！