stm32f103c8t6的PA11的输出PWM波形

可以使用定时器来实现PA11的PWM输出，具体的代码实现可以参考以下示例：

#include "stm32f10x.h"

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

    // 使能GPIOA时钟
    RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOA, ENABLE);

    // 配置PA11为复用推挽输出
    GPIO_InitStructure.GPIO_Pin = GPIO_Pin_11;
    GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF_PP;
    GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
    GPIO_Init(GPIOA, &GPIO_InitStructure);

    // 使能TIM2时钟
    RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM2, ENABLE);

    // 配置TIM2的时基
    TIM_TimeBaseStructure.TIM_Period = 999; // PWM周期为1000个时钟周期
    TIM_TimeBaseStructure.TIM_Prescaler = 71; // 时钟预分频为72
    TIM_TimeBaseStructure.TIM_ClockDivision = TIM_CKD_DIV1;
    TIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Up;
    TIM_TimeBaseInit(TIM2, &TIM_TimeBaseStructure);

    // 配置TIM2的输出比较通道1
    TIM_OCInitStructure.TIM_OCMode = TIM_OCMode_PWM1;
    TIM_OCInitStructure.TIM_OutputState = TIM_OutputState_Enable;
    TIM_OCInitStructure.TIM_Pulse = 500; // 占空比为50%
    TIM_OCInitStructure.TIM_OCPolarity = TIM_OCPolarity_High;
    TIM_OC1Init(TIM2, &TIM_OCInitStructure);

    // 使能TIM2的输出比较通道1
    TIM_OC1PreloadConfig(TIM2, TIM_OCPreload_Enable);

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

int main(void)
{
    PWM_Init();

    while (1)
    {
        // do something
    }
}

这段代码实现了将PA11配置为PWM输出，PWM周期为1000个时钟周期，占空比为50%。其中，时钟预分频为72，可以根据实际情况进行调整。