大侠们，赶紧看一下PWM输出的奇怪问题

kgq398

我使用TIM4输出2路PWM，STM32的端口位PB6 PB7
配置程序一样，但是PB7波形怎么会是PB6的反相呢？
void PWM_Init()
  {
 TIM_TimeBaseInitTypeDef  TIM_TimeBaseStructure;
 TIM_OCInitTypeDef  TIM_OCInitStructure;
 GPIO_InitTypeDef GPIO_InitStructure;

 GPIO_InitStructure.GPIO_Pin = GPIO_PWM;  //选择端口        
   GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF_PP; 
   GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz; //IO时钟频率50M
   GPIO_Init(PORT_PWM, &GPIO_InitStructure);  //生效设定

  /* Time base configuration */  
   TIM_TimeBaseStructure.TIM_Period = PWM_ARR;       
   TIM_TimeBaseStructure.TIM_Prescaler = PWM_PSC;    
   TIM_TimeBaseStructure.TIM_ClockDivision = 0; //设置时钟分频系数：不分频
   TIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Up;  //向上计数模式
 
   TIM_TimeBaseInit(TIM_PWM, &TIM_TimeBaseStructure);
 
   /* PWM1 Mode configuration: Channel1 */
   TIM_OCInitStructure.TIM_OCMode = TIM_OCMode_PWM2;     //配置为PWM模式2
   TIM_OCInitStructure.TIM_OutputState = TIM_OutputState_Enable; 
   TIM_OCInitStructure.TIM_Pulse = 1000;    //设置跳变值，当计数器计数到这个值时，电平发生跳变
   TIM_OCInitStructure.TIM_OCPolarity = TIM_OCPolarity_Low;  //当定时器计数值小于CCR1_Val时为高电平 
   TIM_OC1Init(TIM_PWM, &TIM_OCInitStructure);  //使能通道1
 
   TIM_OC1PreloadConfig(TIM_PWM, TIM_OCPreload_Enable);
 
   /* PWM1 Mode configuration: Channel2 */
   TIM_OCInitStructure.TIM_OutputState = TIM_OutputState_Enable;
   TIM_OCInitStructure.TIM_Pulse = 1000;   //设置通道2的电平跳变值，输出另外一个占空比的PWM 
   TIM_OC2Init(TIM_PWM, &TIM_OCInitStructure);   //使能通道2 
   TIM_OC2PreloadConfig(TIM_PWM, TIM_OCPreload_Enable);
  
   TIM_ARRPreloadConfig(TIM_PWM, ENABLE);    // 使能重载寄存器ARR 
   TIM_Cmd(TIM_PWM, ENABLE);                   //使能定时器   
  }
软件仿真看波形是对的，但是实际用示波器测量的话，就不对，百思不得其解