写一个 STM32F103C8T6 控制按键切换不同占空比的pwm波的代码

这是一份示例代码，你可以使用它作为参考：

#include "stm32f10x.h"

#define LED_PIN GPIO_Pin_13
#define LED_PORT GPIOC

void delay(uint32_t t)
{
    while(t--);
}

void RCC_Config(void)
{
    RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOC, ENABLE);
    RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM3, ENABLE);
}

void GPIO_Config(void)
{
    GPIO_InitTypeDef GPIO_InitStructure;

    GPIO_InitStructure.GPIO_Pin = LED_PIN;
    GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
    GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF_PP;
    GPIO_Init(LED_PORT, &GPIO_InitStructure);
}

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

    TIM_TimeBaseStructure.TIM_Prescaler = 7200-1;
    TIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Up;
    TIM_TimeBaseStructure.TIM_Period = 1000-1;
    TIM_TimeBaseStructure.TIM_ClockDivision = 0;
    TIM_TimeBaseInit(TIM3, &TIM_TimeBaseStructure);

    TIM_OCInitStructure.TIM_OCMode = TIM_OCMode_PWM1;
    TIM_OCInitStructure.TIM_OutputState = TIM_OutputState_Enable;
    TIM_OCInitStructure.TIM_Pulse = 500-1;
    TIM_OCInitStructure.TIM_OCPolarity = TIM_OCPolarity_High;
    TIM_OC3Init(TIM3, &TIM_OCInitStructure);
    TIM_OC3PreloadConfig(TIM3, TIM_OCPreload_Enable);

    TIM_Cmd(TIM3, ENABLE);
}

void SysTick_Handler(void)
{
    static uint8_t flag=0;

    if (flag)
    {
        TIM_SetCompare3(TIM3, 750-1);
        flag = 0;
    }
    else
    {
        TIM_SetCompare3(TIM3, 250-1);
        flag = 1;
    }
}

int main(void)
{
    SystemInit();
    RCC_Config();
    GPIO_Config();
    TIM_Config();

    while(1)
    {
        delay(0xfffff);
    }
}

希望这能对你有所帮助！