IPB6平常为高电平，有信号脉冲低电平有效，PB6要怎么设置引脚


[mw_shl_code=c,true]  GPIO_InitStructure.GPIO_Pin  = WIEGAND_DATA0_GPIO | WIEGAND_DATA1_GPIO;
  GPIO_InitStructure.GPIO_Mode = GPIO_Mode_IN;
  GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_DOWN;
  GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
  GPIO_Init(WIEGAND_PORT, &GPIO_InitStructure);


SYSCFG_EXTILineConfig(WIEGAND_PortSource,EXTI_PinSource6);
  EXTI_InitStructure.EXTI_Line        = EXTI_Line6;
  EXTI_InitStructure.EXTI_Mode = EXTI_Mode_Interrupt;       
  EXTI_InitStructure.EXTI_Trigger = EXTI_Trigger_Rising;
  EXTI_InitStructure.EXTI_LineCmd = ENABLE;
  EXTI_Init(&EXTI_InitStructure);         [/mw_shl_code]