大家好！小弟在调试RS485通讯时，需要使用UART1串口，引脚是PB6、PB7，需要复用及重映射，部分程序如下，为什么不通呢？
GPIO_InitTypeDef GPIO_InitStructure;
  NVIC_InitTypeDef NVIC_InitStructure;
  
    /* Enable GPIO clock */
  RCC_APB2PeriphClockCmd(Modbus_COM_TX_GPIO_CLK | Modbus_COM_RX_GPIO_CLK, ENABLE);
  RCC_APB2PeriphClockCmd(Modbus_COM_CLK, ENABLE);//
    /*UART1  I/O口重映射开启  */
  GPIO_PinRemapConfig(GPIO_Remap_USART1,ENABLE);   //
    /* Configure the NVIC Preemption Priority Bits */  
  NVIC_PriorityGroupConfig(NVIC_PriorityGroup_0);
  
    /* Enable the USARTy Interrupt */
  NVIC_InitStructure.NVIC_IRQChannel = Modbus_COM_IRQn;
  NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = ISR_PRIORITY_MODBUS;
  NVIC_InitStructure.NVIC_IRQChannelSubPriority = 1;
  NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;
  NVIC_Init(&NVIC_InitStructure);