void TIM_Configuration(void)//TIM初始化函数
{
  TIM_TimeBaseInitTypeDef  TIM_TimeBaseStructure;//定时器初始化结构
  TIM_OCInitTypeDef  TIM_OCInitStructure;//通道输出初始化结构 //TIM3初始化
  TIM_DeInit(TIM2);
  TIM_TimeBaseStructure.TIM_Period = 719;        //周期719
  TIM_TimeBaseStructure.TIM_Prescaler = 999;          //时钟分频  
  TIM_TimeBaseStructure.TIM_ClockDivision = 0;      //时钟分割
  TIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Up;//模式
  TIM_TimeBaseInit(TIM2, &TIM_TimeBaseStructure);   //基本初始化
// TIM_ITConfig(TIM2, TIM_IT_CC4, ENABLE);//打开中断，中断需要这行代码
 
//TIM3通道初始化
  TIM_OCStructInit(& TIM_OCInitStructure);                             //默认参数
  TIM_OCInitStructure.TIM_OCMode = TIM_OCMode_PWM1;                    //工作状态，;//配置为PWM1模式
  TIM_OCInitStructure.TIM_OutputState = TIM_OutputState_Enable;         //设定为输出，需要PWM输出才需要这行代码
  TIM_OCInitStructure.TIM_Pulse = 800;                                 //占空长度
  TIM_OCInitStructure.TIM_OCPolarity = TIM_OCPolarity_High;                 //高电平
  TIM_OC4Init(TIM2, &TIM_OCInitStructure);                                 //使用通道4
  TIM_Cmd(TIM2, ENABLE);                                                                          //启动TIM2
}   PA3输出的信号周期为5ms，单个周期内高电平持续时间为0.7ms 这时初始化部分，我想知道的是：使用哪条C语句(或者改变哪个已有的参数)可以改变PWM的占空比 谢谢！ 此帖出自小平头技术问答