PMW上电初始电平求助

只看该作者 · 2014-3-30 17:08

偶是菜鸟，在学习PWM时，相关设置如下：
TIM_OCInitStructure.TIM_OCMode = TIM_OCMode_PWM1;                   //TIM1 脉冲调制模式2
   TIM_OCInitStructure.TIM_OutputState = TIM_OutputState_Enable;    //使能输出比较状态
   TIM_OCInitStructure.TIM_OutputNState = TIM_OutputNState_Enable;    //使能输出比较N状态
   TIM_OCInitStructure.TIM_Pulse = CCR1_Val;                            //比较寄存器的脉冲值
   TIM_OCInitStructure.TIM_OCPolarity = TIM_OCPolarity_High;          //输出比较极性低
   TIM_OCInitStructure.TIM_OCNPolarity = TIM_OCNPolarity_High;          //输出比较N极性低
   TIM_OCInitStructure.TIM_OCIdleState = TIM_OCIdleState_Set;
   TIM_OCInitStructure.TIM_OCNIdleState = TIM_OCIdleState_Reset;

   TIM_OC1Init(TIM2, &TIM_OCInitStructure);
   TIM_OC1PreloadConfig(TIM2, TIM_OCPreload_Enable);
在定时器启用前，pwm口却输出高电平，但我需要启用定时器前pwm口为低电平
跪求大侠相助！