stm32 uart 中断 蜜汁bug

在项目中，使用stm32f103，配置uart1接收RXNE中断，使用DMA来进行UART1的发送。

初始化代码如下：

void uart_init(u32 bound)
{
	GPIO_InitTypeDef GPIO_InitStructure;
	USART_InitTypeDef USART_InitStructure;
	NVIC_InitTypeDef NVIC_InitStructure;

	RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOA, ENABLE);
	RCC_APB2PeriphClockCmd(RCC_APB2Periph_USART1, ENABLE);
	RCC_AHBPeriphClockCmd(RCC_AHBPeriph_DMA1, ENABLE);

	GPIO_InitStructure.GPIO_Pin = GPIO_Pin_9 | GPIO_Pin_11;
	GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF_PP;
	GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
	GPIO_Init(GPIOA, &GPIO_InitStructure);

	GPIO_InitStructure.GPIO_Pin = GPIO_Pin_10 | GPIO_Pin_12;
	GPIO_InitStructure.GPIO_Mode = GPIO_Mode_IN_FLOATING;
	GPIO_Init(GPIOA, &GPIO_InitStructure);	

	USART_InitStructure.USART_BaudRate = bound;//²¨ÌØÂÊÉèÖÃ
	USART_InitStructure.USART_WordLength = USART_WordLength_8b;//×Ö³¤Îª8λÊý¾Ý¸ñʽ
	USART_InitStructure.USART_StopBits = USART_StopBits_1;//Ò»¸öֹͣλ
	USART_InitStructure.USART_Parity = USART_Parity_No;//ÎÞÆæżУÑéλ
	USART_InitStructure.USART_HardwareFlowControl = USART_HardwareFlowControl_RTS_CTS;
	USART_InitStructure.USART_Mode = USART_Mode_Rx | USART_Mode_Tx;	//ÊÕ·¢Ä£Ê½
	USART_Init(USART1, &USART_InitStructure);

	USART_DMACmd(USART1, USART_DMAReq_Tx, ENABLE);

	//USART_ClearFlag(USART1, USART_FLAG_TC);
	USART_ITConfig(USART1, USART_IT_RXNE, ENABLE);//¿ªÆôÏà¹ØÖжÏ
	USART_Cmd(USART1, ENABLE);

	//USART NVIC ÅäÖÃ
	NVIC_InitStructure.NVIC_IRQChannel = USART1_IRQn;
	NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority=2;//ÇÀÕ¼ÓÅÏȼ¶2
	NVIC_InitStructure.NVIC_IRQChannelSubPriority =2;		//×ÓÓÅÏȼ¶2
	NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;			//IRQͨµÀʹÄÜ
	NVIC_Init(&NVIC_InitStructure);	//¸ù¾ÝÖ¸¶¨µÄ²ÎÊý³õʼ»¯VIC¼Ä´æÆ÷

	//DMA
	DMA_InitStructure.DMA_DIR = DMA_DIR_PeripheralDST;
	DMA_InitStructure.DMA_M2M = DMA_M2M_Disable;
	DMA_InitStructure.DMA_MemoryDataSize = DMA_MemoryDataSize_Byte;
	DMA_InitStructure.DMA_MemoryInc = DMA_MemoryInc_Enable;
	DMA_InitStructure.DMA_Mode = DMA_Mode_Normal;
	DMA_InitStructure.DMA_PeripheralBaseAddr = (uint32_t)(&USART1->DR);
	DMA_InitStructure.DMA_PeripheralDataSize = DMA_PeripheralDataSize_Byte;
	DMA_InitStructure.DMA_PeripheralInc = DMA_PeripheralInc_Disable;
	DMA_InitStructure.DMA_Priority = DMA_Priority_High;

	DMA_Cmd(DMA1_Channel4, DISABLE);
	DMA_DeInit(DMA1_Channel4);
	DMA_ITConfig(DMA1_Channel4, DMA_IT_TC, ENABLE);
	NVIC_InitStructure.NVIC_IRQChannel = DMA1_Channel4_IRQn;
	NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority=0;//ÇÀÕ¼ÓÅÏȼ¶0
	NVIC_InitStructure.NVIC_IRQChannelSubPriority =0;		//×ÓÓÅÏȼ¶0
	NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;			//IRQͨµÀʹÄÜ
	NVIC_Init(&NVIC_InitStructure);	//¸ù¾ÝÖ¸¶¨µÄ²ÎÊý³õʼ»¯VIC¼Ä´æÆ÷
}

DMA中断服务函数如下：

void DMA1_Channel4_IRQHandler(void)
{
	if(DMA_GetITStatus(DMA1_IT_TC4))
	{
		DMA_Cmd(DMA1_Channel4, DISABLE);
		DMA_ClearITPendingBit(DMA1_IT_TC4);

		UartDmaBusyFlag = false;
	}
}

UART1中断服务函数如下：

void USART1_IRQHandler(void)
{
	uint8_t Res;
	if(USART_GetITStatus(USART1, USART_IT_RXNE) != RESET)
	{
		Res =USART_ReceiveData(USART1);
		Uart2NrfQueuePush(Res);
	}
    // strange!!!
//    if(USART_GetITStatus(USART1, USART_IT_TC) != RESET)
//    {
//        USART_ClearITPendingBit(USART1, USART_IT_TC);
//        GPIO_ResetBits(GPIOB, GPIO_Pin_8);
//    }
}

如上述UART中断服务函数所示，一旦加入对USART_IT_TC的查询，即使该中断实际上并没有产生，使用keil查看UART1的寄存器，发现TC标志位是置1的。

而更奇怪的是，这种情况下UART1接收的数据会丢掉几个。而只要注释掉这几行代码，一切正常。