参考阅读http://t.csdn.cn/XPF2q
参考视频：
点击查看【bilibili】

一些关键知识

for(pwmVal = 0; pwmVal <= 1000; pwmVal++)
      {
          __HAL_TIM_SetCompare(&htim3, TIM_CHANNEL_1,pwmVal);
          HAL_Delay(1);
      }
      for(pwmVal = 0; pwmVal <= 1000; pwmVal++)
      {
          __HAL_TIM_SetCompare(&htim3, TIM_CHANNEL_1,1000-pwmVal);
          HAL_Delay(1);
      }