目前用stm32做BLDC驱动，PWM输出碰到问题
1、初始化GPIO口复用为TIM 输出脚后，默认即为高电平输出(实际有效电平为高电平)
2、在PWM输出过程中，关闭某一路通道输出，发现该通道与对应互补通道均输出高电平，应为低电平才对
也尝试改过PWM的输出模式及输出极性，没有效果。还是贴下源码吧

void TIM8_PWM_Config(void)
{
    TIM_TimeBaseInitTypeDef  TIM_TimeBaseStructure;
    TIM_OCInitTypeDef  TIM_OCInitStructure;
    TIM_BDTRInitTypeDef TIM_BDTRInitStructure;

   /* TIM8 clock enable */
    RCC_APB2PeriphClockCmd(RCC_APB2Periph_TIM8, ENABLE);

    /* Time Base configuration */
    // ARR = TIM8CLK / ChopperFreq  ChopperFreq:16KHz
    TIM_TimeBaseStructure.TIM_Prescaler = 0;    //预分频 PSC
    TIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Up;
    TIM_TimeBaseStructure.TIM_Period = PWM_PERIOD - 1;    //PWM周期TIM_ARR寄存器
    TIM_TimeBaseStructure.TIM_ClockDivision = 0;
    TIM_TimeBaseStructure.TIM_RepetitionCounter = 0;
    TIM_TimeBaseInit(TIM8, &TIM_TimeBaseStructure);
   

  /* Channel 1, 2,3 and 4 Configuration in PWM mode */
    TIM_OCInitStructure.TIM_OCMode = TIM_OCMode_PWM1;                    //TIM输出通道初始化
    TIM_OCInitStructure.TIM_OutputState = TIM_OutputState_Enable;
    TIM_OCInitStructure.TIM_OutputNState = TIM_OutputState_Enable;
    TIM_OCInitStructure.TIM_Pulse = CH1_PULSE;
    TIM_OCInitStructure.TIM_OCPolarity = TIM_OCPolarity_High;
    TIM_OCInitStructure.TIM_OCNPolarity = TIM_OCNPolarity_High;
    TIM_OCInitStructure.TIM_OCIdleState = TIM_OCIdleState_Reset;
    TIM_OCInitStructure.TIM_OCNIdleState = TIM_OCNIdleState_Reset;
    TIM_OC1Init(TIM8, &TIM_OCInitStructure);

    TIM_OCInitStructure.TIM_Pulse = CH2_PULSE;
    TIM_OC2Init(TIM8, &TIM_OCInitStructure);

    TIM_OCInitStructure.TIM_Pulse = CH3_PULSE;
    TIM_OC3Init(TIM8, &TIM_OCInitStructure);


    TIM_OCInitStructure.TIM_OCMode = TIM_OCMode_PWM2;                    //TIM输出通道4初始化，用来触发AD注入采样
    TIM_OCInitStructure.TIM_OutputState = TIM_OutputState_Disable;                  
    TIM_OCInitStructure.TIM_Pulse = CH1_PULSE;
    TIM_OCInitStructure.TIM_OCPolarity = TIM_OCPolarity_High;           
    TIM_OC4Init(TIM8,&TIM_OCInitStructure);

  /* Automatic Output enable, Break, dead time and lock configuration*/
    TIM_BDTRInitStructure.TIM_OSSRState = TIM_OSSRState_Enable; //死区刹车初始化
    TIM_BDTRInitStructure.TIM_OSSIState = TIM_OSSIState_Enable;
    TIM_BDTRInitStructure.TIM_LOCKLevel = TIM_LOCKLevel_OFF;
    TIM_BDTRInitStructure.TIM_DeadTime = 12;
    TIM_BDTRInitStructure.TIM_Break = TIM_Break_Enable;
    TIM_BDTRInitStructure.TIM_BreakPolarity = TIM_BreakPolarity_High;//TIM_BreakPolarity_Low;
    TIM_BDTRInitStructure.TIM_AutomaticOutput = TIM_AutomaticOutput_Enable;//TIM_AutomaticOutput_Disable;

    TIM_BDTRConfig(TIM8, &TIM_BDTRInitStructure);

     TIM_OC1PreloadConfig(TIM8,TIM_OCPreload_Enable);      //使能捕获比较寄存器预装载（通道1）
    TIM_OC2PreloadConfig(TIM8,TIM_OCPreload_Enable);          //使能捕获比较寄存器预装载（通道2）
    TIM_OC3PreloadConfig(TIM8,TIM_OCPreload_Enable);          //使能捕获比较寄存器预装载（通道3）

    //TIM_ITConfig(TIM8, TIM_IT_COM, ENABLE);   //使能COM事件中断

    TIM_SelectInputTrigger(TIM8, TIM_TS_ITR2);  //输入触发源选择TIM4

    /* TIM8 counter enable */
    TIM_Cmd(TIM8, ENABLE);

    /* Main Output Enable */
    TIM_CtrlPWMOutputs(TIM8, ENABLE);
}

void TIM8_GPIO_Config(void)
{
    GPIO_InitTypeDef GPIO_InitStructure;
    NVIC_InitTypeDef NVIC_InitStructure;
  
    /* GPIOA and GPIOB clocks enable */
    RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_GPIOA | RCC_AHB1Periph_GPIOB | RCC_AHB1Periph_GPIOC, ENABLE);

  /* GPIOC Configuration: Channel 1, 2 and 3 as alternate function push-pull */
    GPIO_InitStructure.GPIO_Pin = GPIO_Pin_6 | GPIO_Pin_7 | GPIO_Pin_8;
    GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF;
    GPIO_InitStructure.GPIO_Speed = GPIO_Speed_100MHz;
    GPIO_InitStructure.GPIO_OType = GPIO_OType_PP;
    GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_NOPULL;  
    GPIO_Init(GPIOC, &GPIO_InitStructure);
  
  /* GPIOE Configuration: Channel 1N as alternate function push-pull */
    GPIO_InitStructure.GPIO_Pin = GPIO_Pin_6;   //BKIN
    GPIO_InitStructure.GPIO_Pin = GPIO_Pin_7;
    GPIO_Init(GPIOA, &GPIO_InitStructure);

  /* GPIOB Configuration:2N and 3N as alternate function push-pull */
    GPIO_InitStructure.GPIO_Pin = GPIO_Pin_14 | GPIO_Pin_15;
    GPIO_Init(GPIOB, &GPIO_InitStructure);

  
  /* Connect TIM pins to AF */
    GPIO_PinAFConfig(GPIOC, GPIO_PinSource6, GPIO_AF_TIM8);     //UH
    GPIO_PinAFConfig(GPIOC, GPIO_PinSource7, GPIO_AF_TIM8);    //VH
    GPIO_PinAFConfig(GPIOC, GPIO_PinSource8, GPIO_AF_TIM8);    //WH
    GPIO_PinAFConfig(GPIOA, GPIO_PinSource7, GPIO_AF_TIM8);    //UL
    GPIO_PinAFConfig(GPIOB, GPIO_PinSource14, GPIO_AF_TIM8);    //VL
    GPIO_PinAFConfig(GPIOB, GPIO_PinSource15, GPIO_AF_TIM8);    //WL   
    GPIO_PinAFConfig(GPIOA, GPIO_PinSource6, GPIO_AF_TIM8);    //BKIN

  /* Enable the TIM8 Trigger and commutation interrupt */
    NVIC_InitStructure.NVIC_IRQChannel = TIM8_TRG_COM_TIM14_IRQn;
    NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 0;
    NVIC_InitStructure.NVIC_IRQChannelSubPriority = 0;
    NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;
    NVIC_Init(&NVIC_InitStructure);   
}

void MC2_Commutation(uint8_t dir, uint8_t tab)
{
    switch(tab)               
    {
        case 5:     //BA(1L,2H)
            /*  Channel1 configuration */
            TIM_SelectOCxM(TIM8, TIM_Channel_1, TIM_OCMode_Active);
            TIM_CCxCmd(TIM8, TIM_Channel_1, TIM_CCx_Disable);
            TIM_CCxNCmd(TIM8, TIM_Channel_1, TIM_CCxN_Enable);

            /*  Channel2 configuration */
            TIM_SelectOCxM(TIM8, TIM_Channel_2, TIM_OCMode_PWM1);
            TIM_CCxCmd(TIM8, TIM_Channel_2, TIM_CCx_Enable);
            TIM_CCxNCmd(TIM8, TIM_Channel_2, TIM_CCxN_Disable);

            /*  Channel3 configuration */
            TIM_CCxCmd(TIM8, TIM_Channel_3, TIM_CCx_Disable);
            TIM_CCxNCmd(TIM8, TIM_Channel_3, TIM_CCxN_Disable);
            break;

      case 4:
           ......

        default:
            break;
           
        }
}

你这个编译通不过吧!
 RCC_APB2PeriphClockCmd(   RCC_APB2Periph_AFIO
       | RCC_APB2Periph_GPIOA
       | RCC_APB2Periph_GPIOB
       | RCC_APB2Periph_GPIOC
       | RCC_APB2Periph_GPIOD , ENABLE );