STM32 uses DAC+DMA+TIMER to output sine wave

The board used is STM32F407, and the program refers to the program in the DAC_SignalsGeneration folder of the STM32F4xx firmware library. The official routines use the Escalator Wave trapezoidal wave, Sine Wave sine wave of the DAC's disabled generation wave (DAC_WaveGeneration_None) and the built-in Noise Wave (DAC_WaveGeneration_Noise), Triangle Wave (DAC_WaveGeneration_Triangle) of stm32.

The following mainly talks about the configuration of output sine wave.

Array of sinusoidal voltages

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};

After plotting the above array using Matlab, it looks like this:

The following is the program to configure DAC channel 2, turn on DMA, and set TIMER6 to trigger DAC

void DAC_Ch2_SineWaveConfig(void)

{

  DMA_InitTypeDef DMA_InitStructure;

  DAC_InitTypeDef  DAC_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);

}

Below is the configuration program for timer 6

The timer update frequency is 84M/(0xFF+1)=328KHZ

void TIM6_Config(void)

{

  TIM_TimeBaseInitTypeDef    TIM_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);

}

Because our sine waveform is composed of 32 points, the frequency of the output sine waveform is 328K/32=10.25K

Verify with an oscilloscope, as shown below