stm32f407 pwm变化输出代码

好的，以下是一个基本的STM32F407 PWM变化输出代码供您参考：

#include "stm32f4xx.h"

int main(void)
{
    // Enable GPIO and PWM clock
    RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_GPIOA, ENABLE);
    RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM2, ENABLE);

    // Initialize GPIO pins
    GPIO_InitTypeDef GPIO_InitStruct;
    GPIO_InitStruct.GPIO_Pin = GPIO_Pin_5;
    GPIO_InitStruct.GPIO_Mode = GPIO_Mode_AF;
    GPIO_InitStruct.GPIO_Speed = GPIO_Speed_50MHz;
    GPIO_InitStruct.GPIO_OType = GPIO_OType_PP;
    GPIO_InitStruct.GPIO_PuPd = GPIO_PuPd_UP;
    GPIO_Init(GPIOA, &GPIO_InitStruct);

    GPIO_PinAFConfig(GPIOA, GPIO_PinSource5, GPIO_AF_TIM2);

    // Initialize PWM Timer
    TIM_TimeBaseInitTypeDef TIM_InitStruct;
    TIM_InitStruct.TIM_Prescaler = 84;
    TIM_InitStruct.TIM_CounterMode = TIM_CounterMode_Up;
    TIM_InitStruct.TIM_Period = 1000;
    TIM_InitStruct.TIM_ClockDivision = TIM_CKD_DIV1;
    TIM_TimeBaseInit(TIM2, &TIM_InitStruct);

    // Configure PWM channel
    TIM_OCInitTypeDef TIM_OC_InitStruct;
    TIM_OC_InitStruct.TIM_OCMode = TIM_OCMode_PWM1;
    TIM_OC_InitStruct.TIM_OutputState = TIM_OutputState_Enable;
    TIM_OC_InitStruct.TIM_Pulse = 500;
    TIM_OC_InitStruct.TIM_OCPolarity = TIM_OCPolarity_High;
    TIM_OC1Init(TIM2, &TIM_OC_InitStruct);

    // Enable Output Compare Preload register on CCR1
    TIM_OC1PreloadConfig(TIM2, TIM_OCPreload_Enable);

    // Start PWM Timer
    TIM_Cmd(TIM2, ENABLE);

    while (1) {
        // Update PWM pulse width
        for (int i = 500; i <= 1000; i += 20) {
            TIM_SetCompare1(TIM2, i);
            for (int j = 0; j < 200000; j++);
        }
    }
}

这个代码通过GPIO初始化了第一个PWM通道(PA5)，然后使用了定时器(TIM2)进行了PWM的配置和控制。每隔20个单位的时间，代码中更新了PWM脉冲的宽度，从而改变输出的信号的占空比，从而控制设备。