stm32f4dacdma正弦波输出代码

要实现stm32f4dacdma正弦波输出，需要以下步骤：

1. 配置DAC通道和DMA通道，使能时钟

在使用DAC和DMA前，需要先使能相应的时钟。对于DAC来说，需要使能DAC时钟和GPIO时钟。对于DMA来说，需要使能DMA时钟。同时也需要配置好DAC通道和DMA通道。

2. 构建正弦波表并放入内存

正弦波表是用来存储一段正弦波的数据。可以使用公式y=sin(2πx/N)生成正弦波表，其中N是正弦波表大小，x是当前位置，y是对应的采样值。然后将正弦波表数据放入内存中。

3. 配置DMA传输数据

使用DMA将内存中的正弦波表数据传输到DAC数据寄存器中。可以配置DMA的传输模式、方向、缓存等参数。

4. 设置DAC触发模式

设置DAC触发模式为DMA触发，并选择DMA通道。

5. 启动DAC和DMA传输

启动DAC和DMA传输即可输出正弦波信号。

总体代码示例：

#define SAMPLE_RATE 100
#define TABLE_SIZE 128

uint16_t sinetable[TABLE_SIZE];

void build_sinetable()
{
    for(int i = 0; i < TABLE_SIZE; i++)
    {
        float tmp = sinf(2 * PI * i / TABLE_SIZE) * 2047 + 2047;
        sinetable[i] = (uint16_t)tmp;
    }
}

void DAC_DMA_Init()
{
    RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_GPIOA, ENABLE);
    RCC_APB1PeriphClockCmd(RCC_APB1Periph_DAC, ENABLE);
    RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_DMA1, ENABLE);

    GPIO_InitTypeDef GPIO_InitStructure;
    DAC_InitTypeDef DAC_InitStructure;
    DMA_InitTypeDef DMA_InitStructure;

    GPIO_InitStructure.GPIO_Pin = GPIO_Pin_4 | GPIO_Pin_5;
    GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AN;
    GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_NOPULL;
    GPIO_Init(GPIOA, &GPIO_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_1, &DAC_InitStructure);
    DAC_Cmd(DAC_Channel_1, ENABLE);

    DMA_DeInit(DMA1_Stream5);
    DMA_InitStructure.DMA_Channel = DMA_Channel_7;
    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_MemoryInc = DMA_MemoryInc_Enable;
    DMA_InitStructure.DMA_PeripheralInc = DMA_PeripheralInc_Disable;
    DMA_InitStructure.DMA_BufferSize = TABLE_SIZE;
    DMA_InitStructure.DMA_PeripheralBaseAddr = (uint32_t)&(DAC->DHR12R1);
    DMA_InitStructure.DMA_Memory0BaseAddr = (uint32_t)sinetable;
    DMA_InitStructure.DMA_DIR = DMA_DIR_MemoryToPeripheral;
    DMA_Init(DMA1_Stream5, &DMA_InitStructure);

    DAC_DMACmd(DAC_Channel_1, ENABLE);

    TIM_TimeBaseInitTypeDef TIM_TimeBaseStructure;
    RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM6, ENABLE);
    TIM_TimeBaseStructInit(&TIM_TimeBaseStructure);
    TIM_TimeBaseStructure.TIM_Period = SystemCoreClock / SAMPLE_RATE / TABLE_SIZE - 1;
    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);

    DMA_Cmd(DMA1_Stream5, ENABLE);
}