stm32f407pwm输出标准库

要使用STM32F407的PWM输出功能，可以使用标准库中的TIM库。具体步骤如下：

1. 初始化TIM时钟和GPIO引脚
2. 配置TIM为PWM模式
3. 配置PWM输出参数，如占空比和频率
4. 启动TIM

以下是一个简单的示例代码：

#include "stm32f4xx.h"

void TIM_Config(void)
{
    GPIO_InitTypeDef GPIO_InitStructure;
    TIM_TimeBaseInitTypeDef TIM_TimeBaseStructure;
    TIM_OCInitTypeDef TIM_OCInitStructure;

    // 使能TIM时钟和GPIO时钟
    RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM2, ENABLE);
    RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_GPIOA, ENABLE);

    // 配置GPIO引脚为复用功能
    GPIO_InitStructure.GPIO_Pin = GPIO_Pin_5;
    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);

    // 配置GPIO复用映射
    GPIO_PinAFConfig(GPIOA, GPIO_PinSource5, GPIO_AF_TIM2);

    // 配置TIM基本参数
    TIM_TimeBaseStructure.TIM_Period = 999; // PWM周期为1000个计数器时钟周期
    TIM_TimeBaseStructure.TIM_Prescaler = 83; // 计数器时钟频率为84MHz/84=1MHz
    TIM_TimeBaseStructure.TIM_ClockDivision = 0;
    TIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Up;
    TIM_TimeBaseInit(TIM2, &TIM_TimeBaseStructure);

    // 配置TIM为PWM模式
    TIM_OCInitStructure.TIM_OCMode = TIM_OCMode_PWM1;
    TIM_OCInitStructure.TIM_OutputState = TIM_OutputState_Enable;
    TIM_OCInitStructure.TIM_Pulse = 500; // 初始占空比为50%
    TIM_OCInitStructure.TIM_OCPolarity = TIM_OCPolarity_High;
    TIM_OC1Init(TIM2, &TIM_OCInitStructure);

    // 启动TIM
    TIM_Cmd(TIM2, ENABLE);
}

int main(void)
{
    TIM_Config();

    while (1) {
        // do something
    }
}