stm32f407dac输出正弦波

要在STM32F407DAC输出正弦波，可以通过以下步骤实现：

1. 定义一个正弦波表，可以使用Excel等工具生成。

2. 配置DAC的输出引脚和时钟，并启用DAC使能。

3. 配置DAC的DMA，将正弦波表数据传输到DAC数据寄存器。

4. 启动DAC的DMA传输，开始输出正弦波。

下面是一个简单的示例代码：

#include "stm32f4xx.h"

#define TABLE_SIZE 256

const uint16_t sinTable[TABLE_SIZE] = { /* 正弦波表数据 */ };

void dac_init(void)
{
    GPIO_InitTypeDef GPIO_InitStructure;
    DAC_InitTypeDef DAC_InitStructure;

    /* 使能GPIO和DAC的时钟 */
    RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_GPIOA, ENABLE);
    RCC_APB1PeriphClockCmd(RCC_APB1Periph_DAC, ENABLE);

    /* 配置PA4引脚为模拟输出 */
    GPIO_InitStructure.GPIO_Pin = GPIO_Pin_4;
    GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AN;
    GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_NOPULL;
    GPIO_Init(GPIOA, &GPIO_InitStructure);

    /* 配置DAC输出参数 */
    DAC_InitStructure.DAC_Trigger = DAC_Trigger_None;
    DAC_InitStructure.DAC_WaveGeneration = DAC_WaveGeneration_None;
    DAC_InitStructure.DAC_OutputBuffer = DAC_OutputBuffer_Enable;
    DAC_Init(DAC_Channel_1, &DAC_InitStructure);

    /* 使能DAC */
    DAC_Cmd(DAC_Channel_1, ENABLE);
}

void dma_init(void)
{
    DMA_InitTypeDef DMA_InitStructure;

    /* 使能DMA和DAC的时钟 */
    RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_DMA1, ENABLE);

    /* 配置DMA通道 */
    DMA_InitStructure.DMA_Channel = DMA_Channel_7;
    DMA_InitStructure.DMA_PeripheralBaseAddr = (uint32_t)&DAC->DHR12R1;
    DMA_InitStructure.DMA_Memory0BaseAddr = (uint32_t)sinTable;
    DMA_InitStructure.DMA_DIR = DMA_DIR_MemoryToPeripheral;
    DMA_InitStructure.DMA_BufferSize = TABLE_SIZE;
    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_Stream5, &DMA_InitStructure);

    /* 使能DMA通道 */
    DMA_Cmd(DMA1_Stream5, ENABLE);
}

int main(void)
{
    dac_init();
    dma_init();

    while (1) {
        /* 循环等待 */
    }
}

在上面的代码中，我们使用DMA将正弦波表数据传输到DAC数据寄存器，实现了正弦波的输出。