STM32利用DAC+DMA+TIMER 輸出正弦波
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
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