TIM4 PWM输出波形不正常

void TIM4_GPIO_Config(void) 

{

  GPIO_InitTypeDef GPIO_InitStructure;



        /* TIM2 clock enable */

        //PCLK1经过2倍频后作为TIM3的时钟源等于72MHz

  RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM4, ENABLE); 

  /* GPIOA and GPIOB clock enable */

  RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOB | RCC_APB2Periph_AFIO, ENABLE); 



  /*GPIOA Configuration: TIM2 channel 1 and 2 as alternate function push-pull */

  GPIO_InitStructure.GPIO_Pin =  GPIO_Pin_6 | GPIO_Pin_7 | GPIO_Pin_8 | GPIO_Pin_9;

  GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF_PP;                    // 复用推挽输出

  GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;



  GPIO_Init(GPIOB, &GPIO_InitStructure);

}



void TIM4_Mode_Config(void)

{

        TIM_TimeBaseInitTypeDef  TIM_TimeBaseStructure;

  TIM_OCInitTypeDef  TIM_OCInitStructure;

        NVIC_InitTypeDef NVIC_InitStructure;

        

        RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM4,ENABLE);

        

        TIM_DeInit(TIM4);//Use TIM_DeInit () function to set Timer as the default value;

  TIM_TimeBaseStructure.TIM_Prescaler = 1-1;//预分频 To set the prescaler coefficient

  TIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Up;//

  TIM_TimeBaseStructure.TIM_Period = Fcount;//

  TIM_TimeBaseStructure.TIM_ClockDivision = TIM_CKD_DIV1;//

  TIM_TimeBaseStructure.TIM_RepetitionCounter = 0;//

  TIM_TimeBaseInit(TIM4,&TIM_TimeBaseStructure);//

        

        TIM_ARRPreloadConfig(TIM4,ENABLE);                          

  

  TIM_OCInitStructure.TIM_OCMode = TIM_OCMode_PWM1;

  TIM_OCInitStructure.TIM_OutputState = TIM_OutputState_Enable;

  TIM_OCInitStructure.TIM_OutputNState = TIM_OutputState_Disable;

  TIM_OCInitStructure.TIM_OCPolarity = TIM_OCPolarity_High;//不反相输出

  TIM_OCInitStructure.TIM_OCNPolarity = TIM_OCNPolarity_Low;

  TIM_OCInitStructure.TIM_OCIdleState = TIM_OCIdleState_Reset;

  TIM_OCInitStructure.TIM_OCNIdleState = TIM_OCIdleState_Reset;

                

////////////////////////////////////////////////////////////////////////////////////

  TIM_OCInitStructure.TIM_OCMode = TIM_OCMode_PWM1;

  TIM_OCInitStructure.TIM_Pulse = 0;

  TIM_OC1Init(TIM4,&TIM_OCInitStructure);

  TIM_OC1PreloadConfig(TIM4, TIM_OCPreload_Disable);

        

        TIM_OCInitStructure.TIM_OCMode = TIM_OCMode_PWM1;

  TIM_OCInitStructure.TIM_Pulse = 0;

  TIM_OC2Init(TIM4,&TIM_OCInitStructure);

  TIM_OC2PreloadConfig(TIM4, TIM_OCPreload_Disable);



        TIM_OCInitStructure.TIM_OCMode = TIM_OCMode_PWM1;

  TIM_OCInitStructure.TIM_Pulse = 0;

  TIM_OC3Init(TIM4,&TIM_OCInitStructure);

  TIM_OC3PreloadConfig(TIM4, TIM_OCPreload_Disable);



        TIM_OCInitStructure.TIM_OCMode = TIM_OCMode_PWM1;

  TIM_OCInitStructure.TIM_Pulse = 0;        //设置通道4的电平跳变值，输出另外一个占空比的PWM

  TIM_OC4Init(TIM4, &TIM_OCInitStructure);        //使能通道4

  TIM_OC4PreloadConfig(TIM4, TIM_OCPreload_Disable);



        TIM_ITConfig(TIM4,TIM_IT_Update,ENABLE ); //使能指定的TIM4中断,允许更新中断

        //中断优先级NVIC设置

        NVIC_InitStructure.NVIC_IRQChannel = TIM4_IRQn;  //TIM4中断

        NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 1;  //先占优先级0级

        NVIC_InitStructure.NVIC_IRQChannelSubPriority = 0;  //从优先级3级

        NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE; //IRQ通道被使能

        NVIC_Init(&NVIC_InitStructure);  //初始化NVIC寄存器



  TIM_Cmd(TIM4,ENABLE);

}