stm32 spwm 代码

以下是一个简单的 STM32 SPWM 代码示例，使用定时器和 DMA 控制 PWM 的输出：

#include "stm32f4xx.h"

#define FREQ 20000 // PWM 频率
#define ARR (SystemCoreClock / FREQ) // 自动重装值

#define DUTY_CYCLE 50 // 占空比
#define CCR_VAL ((ARR - 1) * DUTY_CYCLE / 100) // 比较值

#define BUFFER_SIZE 2 // DMA 缓冲区大小

uint16_t buffer[BUFFER_SIZE] = {0, CCR_VAL}; // DMA 缓冲区

void init_timer_pwm(void)
{
    GPIO_InitTypeDef GPIO_InitStructure;
    TIM_TimeBaseInitTypeDef TIM_TimeBaseStructure;
    TIM_OCInitTypeDef TIM_OCInitStructure;
    DMA_InitTypeDef DMA_InitStructure;

    // 使能 GPIO 和定时器时钟
    RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_GPIOA, ENABLE);
    RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM2, ENABLE);

    // 配置 GPIO 引脚
    GPIO_InitStructure.GPIO_Pin = GPIO_Pin_0;
    GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF;
    GPIO_InitStructure.GPIO_Speed = GPIO_Speed_100MHz;
    GPIO_InitStructure.GPIO_OType = GPIO_OType_PP;
    GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_UP;
    GPIO_Init(GPIOA, &GPIO_InitStructure);

    // 将引脚复用为定时器输出
    GPIO_PinAFConfig(GPIOA, GPIO_PinSource0, GPIO_AF_TIM2);

    // 配置定时器
    TIM_TimeBaseStructure.TIM_Period = ARR - 1;
    TIM_TimeBaseStructure.TIM_Prescaler = 0;
    TIM_TimeBaseStructure.TIM_ClockDivision = TIM_CKD_DIV1;
    TIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Up;
    TIM_TimeBaseInit(TIM2, &TIM_TimeBaseStructure);

    // 配置 PWM 输出通道
    TIM_OCInitStructure.TIM_OCMode = TIM_OCMode_PWM1;
    TIM_OCInitStructure.TIM_OutputState = TIM_OutputState_Enable;
    TIM_OCInitStructure.TIM_Pulse = CCR_VAL;
    TIM_OCInitStructure.TIM_OCPolarity = TIM_OCPolarity_High;
    TIM_OC1Init(TIM2, &TIM_OCInitStructure);

    // 启用 DMA 控制 PWM 输出
    TIM_DMACmd(TIM2, TIM_DMA_CC1, ENABLE);

    // 配置 DMA 控制 PWM 输出
    RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_DMA1, ENABLE);
    DMA_InitStructure.DMA_Channel = DMA_Channel_3;
    DMA_InitStructure.DMA_PeripheralBaseAddr = (uint32_t) &TIM2->CCR1;
    DMA_InitStructure.DMA_Memory0BaseAddr = (uint32_t) buffer;
    DMA_InitStructure.DMA_DIR = DMA_DIR_MemoryToPeripheral;
    DMA_InitStructure.DMA_BufferSize = BUFFER_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_Stream4, &DMA_InitStructure);

    // 启动 DMA
    DMA_Cmd(DMA1_Stream4, ENABLE);

    // 启动定时器
    TIM_Cmd(TIM2, ENABLE);
}

int main(void)
{
    init_timer_pwm();

    while (1) {
        // 在这里修改缓冲区的值，即可改变 PWM 的占空比
        buffer[1] = (ARR - 1) * 75 / 100;
        buffer[0] = ARR - buffer[1] - 1;

        // 延时
        for (int i = 0; i < 100000; i++);
    }
}

该代码使用了 STM32 的 TIM2 定时器和 DMA 控制 PWM 输出，可以通过修改缓冲区的值来改变 PWM 的占空比。注意，上述代码只是一个简单的示例，实际应用中需要根据具体的硬件和需求来进行修改和优化。