stm32 DAC单通道正弦波

要在STM32上输出DAC单通道正弦波，可以使用STM32的DAC和定时器模块。具体步骤如下：

1. 配置DAC通道和GPIO引脚
2. 配置定时器模块，选择合适的时钟源和分频系数，设置自动重载值和计数器初值
3. 在定时器中断服务函数中更新DAC输出值，可以使用查表法或者计算法生成正弦波数据
以下是一个简单的代码示例：

#include "stm32f4xx.h"

#define DAC_DHR12R1_ADDRESS    0x40007408

const uint16_t sin_table[256] = {0, 402, 804, 1206, 1608, 2010, 2411, 2813, 3214, 3615, 4016, 4416, 4816, 5215, 5614, 6012,
                                 6410, 6807, 7203, 7599, 7994, 8388, 8781, 9173, 9564, 9954, 10343, 10731, 11117, 11502, 11886, 12268,
                                 12649, 13028, 13406, 13782, 14157, 14530, 14901, 15271, 15639, 16005, 16369, 16731, 17091, 17449, 17805, 18159,
                                 18511, 18861, 19208, 19553, 19896, 20237, 20575, 20911, 21244, 21575, 21903, 22228, 22551, 22871, 23188, 23502,
                                 23813, 24121, 24426, 24728, 25027, 25322, 25614, 25902, 26187, 26468, 26745, 27018, 27288, 27554, 27816, 28074,
                                 28328, 28578, 28824, 29066, 29304, 29538, 29767, 29992, 30212, 30428, 30639, 30846, 31048, 31245, 31438, 31625,
                                 31808, 31986, 32159, 32327, 32490, 32647, 32700, 32767, 32700, 32647, 32490, 32327, 32159, 31986, 31808, 31625,
                                 31438, 31245, 31048, 30846, 30639, 30428, 30212, 29992, 29767, 29538, 29304, 29066, 28824, 28578, 28328, 28074,
                                 27816, 27554, 27288, 27018, 26745, 26468, 26187, 25902, 25614, 25322, 25027, 24728, 24426, 24121, 23813, 23502,
                                 23188, 22871, 22551, 22228, 21903, 21575, 21244, 20911, 20575, 20237, 19896, 19553, 19208, 18861, 18511, 18159,
                                 17805, 17449, 17091, 16731, 16369, 16005, 15639, 15271, 14901, 14530, 14157, 13782, 13406, 13028, 12649, 12268,
                                 11886, 11502, 11117, 10731, 10343, 9954, 9564, 9173, 8781, 8388, 7994, 7599, 7203, 6807, 6410,
                                 6012, 5614, 5215, 4816, 4416, 4016, 3615, 3214, 2813, 2411, 2010, 1608, 1206, 804, 402,
                                 0, -402, -804, -1206, -1608, -2010, -2411, -2813, -3214, -3615, -4016, -4416, -4816, -5215, -5614, -6012,
                                 -6410, -6807, -7203, -7599, -7994, -8388, -8781, -9173, -9564, -9954, -10343,-10731,-11117,-11502,-11886,-12268,
                                 -12649,-13028,-13406,-13782,-14157,-14530,-14901,-15271,-15639,-16005,-16369,-16731,-17091,-17449,-17805,-18159,-18511,-18861,
                                 -19208,-19553,-19896,-20237,-20575,-20911,-21244,-21575,-21903,-22228,-22551,-22871,-23188,-23502,-23813,-24121,-24426,-24728,
                                 -25027,-25322,-25614,-25902,-26187,-26468,-26745,-27018,-27288,-27554,-27816,-28074,-28328,-28578,-28824,-29066,-29304,-29538,
                                 -29767,-29992,-30212,-30428,-30639,-30846,-31048,-31245,-31438,-31625,-31808,-31986,-32159,-32327,-32490,-32647,-32700,-32767};

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

    RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_GPIOA, ENABLE);
    RCC_APB1PeriphClockCmd(RCC_APB1Periph_DAC, ENABLE);

    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);

    DAC_InitStructure.DAC_Trigger = DAC_Trigger_T2_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);
}

void TIM_Config(void)
{
    TIM_TimeBaseInitTypeDef TIM_TimeBaseStructure;
    NVIC_InitTypeDef NVIC_InitStructure;

    RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM2, ENABLE);

    TIM_TimeBaseStructure.TIM_Period = 255;
    TIM_TimeBaseStructure.TIM_Prescaler = 83;
    TIM_TimeBaseStructure.TIM_ClockDivision = TIM_CKD_DIV1;
    TIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Up;
    TIM_TimeBaseInit(TIM2, &TIM_TimeBaseStructure);

    TIM_SelectOutputTrigger(TIM2, TIM_TRGOSource_Update);

    NVIC_InitStructure.NVIC_IRQChannel = TIM2_IRQn;
    NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 0;
    NVIC_InitStructure.NVIC_IRQChannelSubPriority = 0;
    NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;
    NVIC_Init(&NVIC_InitStructure);

    TIM_ITConfig(TIM2, TIM_IT_Update, ENABLE);

    TIM_Cmd(TIM2, ENABLE);
}

void TIM2_IRQHandler(void)
{
    static uint8_t index = 0;

    DAC_SetChannel1Data(DAC_Align_12b_R, sin_table[index]);

    index++;
    if (index >= 256)
        index = 0;

    TIM_ClearITPendingBit(TIM2, TIM_IT_Update);
}

int main(void)
{
    DAC_Config();
    TIM_Config();

    while (1)
    {
    }
}