写出用stm32f103c8t6输出pwm信号的代码

以下是用stm32f103c8t6输出pwm信号的示例代码：

#include "stm32f10x.h"

int main(void) {
  RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOA, ENABLE);   //启用GPIOA时钟
  RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM2, ENABLE);     //启用TIM2时钟

  GPIO_InitTypeDef GPIO_InitStructure;
  TIM_TimeBaseInitTypeDef TIM_TimeBaseStructure;
  TIM_OCInitTypeDef TIM_OCInitStructure;

  //配置GPIO口为复用推挽输出
  GPIO_InitStructure.GPIO_Pin = GPIO_Pin_0;
  GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF_PP;
  GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
  GPIO_Init(GPIOA, &GPIO_InitStructure);

  //初始化TIM2
  TIM_TimeBaseStructure.TIM_Period = 999;                //设置计数器的自动重载值
  TIM_TimeBaseStructure.TIM_Prescaler = 71;              //设置时钟分频系数
  TIM_TimeBaseStructure.TIM_ClockDivision = 0;           //设置时钟分割
  TIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Up;  //向上计数模式
  TIM_TimeBaseInit(TIM2, &TIM_TimeBaseStructure);

  //配置TIM2的PWM通道
  TIM_OCInitStructure.TIM_OCMode = TIM_OCMode_PWM1;      //PWM模式1
  TIM_OCInitStructure.TIM_OutputState = TIM_OutputState_Enable; //使能PWM输出
  TIM_OCInitStructure.TIM_Pulse = 499;                   //设置脉冲宽度
  TIM_OCInitStructure.TIM_OCPolarity = TIM_OCPolarity_High;    //输出极性高
  TIM_OC1Init(TIM2, &TIM_OCInitStructure);               //初始化通道1

  TIM_Cmd(TIM2, ENABLE);                         //启用定时器

  while(1);
}

此代码将在PA0引脚输出一个1kHz的PWM信号，占空比为50%。在此示例中，TIM2用于生成PWM信号，时钟频率为72MHz，预分频系数为71，使得定时器的时钟频率为1MHz。自动重载值设置为999，这意味着每1000个时钟周期，定时器将产生一个更新事件。通道1被配置为PWM输出，占空比为50%。最后，从while循环中退出。