使用的是STM32F407的板子，程序參考的是STM32F4xx固件庫的DAC_SignalsGeneration文件夾下的程序。官方例程分別使用了DAC的禁止生成波（DAC_WaveGeneration_None）的Escalator Wave梯形波,Sine Wave正弦波和stm32內(nèi)置的的Noise Wave(DAC_WaveGeneration_Noise)，Triangle Wave(DAC_WaveGeneration_Triangle)。

下面主要說一下輸出正弦波的配置。

正弦電壓的數(shù)組

const uint16_t aSine12bit[32] = {

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};

把以上數(shù)組用matlab畫出后，如下圖所示：

下面是配置DAC通道2的程序，開DMA,設(shè)置TIMER6觸發(fā)DAC

void DAC_Ch2_SineWaveConfig(void)

{

DMA_InitTypeDef DMA_InitStructure;

DAC_InitTypeDefDAC_InitStructure;

DAC_InitStructure.DAC_Trigger = DAC_Trigger_T6_TRGO;

DAC_InitStructure.DAC_WaveGeneration = DAC_WaveGeneration_None;

DAC_InitStructure.DAC_OutputBuffer = DAC_OutputBuffer_Enable;

DAC_Init(DAC_Channel_2, &DAC_InitStructure);

DMA_DeInit(DMA1_Stream6);

DMA_InitStructure.DMA_Channel = DMA_Channel_7;

DMA_InitStructure.DMA_PeripheralBaseAddr = (uint32_t)DAC_DHR12R2_ADDRESS;

DMA_InitStructure.DMA_Memory0BaseAddr = (uint32_t)&aSine12bit;

DMA_InitStructure.DMA_DIR = DMA_DIR_MemoryToPeripheral;

DMA_InitStructure.DMA_BufferSize = 32;

DMA_InitStructure.DMA_PeripheralInc = DMA_PeripheralInc_Disable;

DMA_InitStructure.DMA_MemoryInc = DMA_MemoryInc_Enable;

DMA_InitStructure.DMA_PeripheralDataSize = DMA_PeripheralDataSize_HalfWord;

DMA_InitStructure.DMA_MemoryDataSize = DMA_MemoryDataSize_HalfWord;

DMA_InitStructure.DMA_Mode = DMA_Mode_Circular;

DMA_InitStructure.DMA_Priority = DMA_Priority_High;

DMA_InitStructure.DMA_FIFOMode = DMA_FIFOMode_Disable;

DMA_InitStructure.DMA_FIFOThreshold = DMA_FIFOThreshold_HalfFull;

DMA_InitStructure.DMA_MemoryBurst = DMA_MemoryBurst_Single;

DMA_InitStructure.DMA_PeripheralBurst = DMA_PeripheralBurst_Single;

DMA_Init(DMA1_Stream6, &DMA_InitStructure);

DMA_Cmd(DMA1_Stream6, ENABLE);

DAC_Cmd(DAC_Channel_2, ENABLE);

DAC_DMACmd(DAC_Channel_2, ENABLE);

}

下面是定時器6的配置程序

定時器更新頻率是84M/(0xFF+1)=328KHZ

void TIM6_Config(void)

{

TIM_TimeBaseInitTypeDefTIM_TimeBaseStructure;

RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM6, ENABLE);

TIM_TimeBaseStructInit(&TIM_TimeBaseStructure);

TIM_TimeBaseStructure.TIM_Period = 0xFF;

TIM_TimeBaseStructure.TIM_Prescaler = 0;

TIM_TimeBaseStructure.TIM_ClockDivision = 0;

TIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Up;

TIM_TimeBaseInit(TIM6, &TIM_TimeBaseStructure);

TIM_SelectOutputTrigger(TIM6, TIM_TRGOSource_Update);

TIM_Cmd(TIM6, ENABLE);

}

因為我們的正弦波形是由32個點構(gòu)成，所以輸出的正弦波形的頻率是328K/32=10.25K

用示波器驗證，如下圖所示