usart2 重映射

今天拾起闲置很久的灰机，测试发现nrf2401坏掉，重新淘宝。还发现机上搭载的usart1坏掉，换成usart2，发现端口被电机占用，重映射到PD5，PD6

关键是后面两句不要忘记了

	RCC_APB1PeriphClockCmd(RCC_APB1Periph_USART2, ENABLE);
	RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOD, ENABLE);	//使能USART2，GPIOD时钟
	RCC_APB2PeriphClockCmd(RCC_APB2Periph_AFIO,ENABLE);
	GPIO_PinRemapConfig(GPIO_Remap_USART2, ENABLE);

修改后的原子printf代码usart.c

void uart_init(u32 bound){
  //GPIO端口设置
	GPIO_InitTypeDef GPIO_InitStructure;
	USART_InitTypeDef USART_InitStructure;
	NVIC_InitTypeDef NVIC_InitStructure;

	RCC_APB1PeriphClockCmd(RCC_APB1Periph_USART2, ENABLE);
	RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOD, ENABLE);	//使能USART2，GPIOD时钟
	RCC_APB2PeriphClockCmd(RCC_APB2Periph_AFIO,ENABLE);
	GPIO_PinRemapConfig(GPIO_Remap_USART2, ENABLE);

	//USART2_TX   GPIOD5
  GPIO_InitStructure.GPIO_Pin = GPIO_Pin_5; //PD5
  GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
  GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF_PP;	//复用推挽输出
  GPIO_Init(GPIOD, &GPIO_InitStructure);//初始化GPIOD5

  //USART2_RX	  GPIOD6初始化
  GPIO_InitStructure.GPIO_Pin = GPIO_Pin_6;//PD6
  GPIO_InitStructure.GPIO_Mode = GPIO_Mode_IN_FLOATING;//浮空输入
  GPIO_Init(GPIOD, &GPIO_InitStructure);//初始化GPIOD6

  //Usart2 NVIC 配置
  NVIC_InitStructure.NVIC_IRQChannel = USART2_IRQn;
	NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority=3 ;//抢占优先级3
	NVIC_InitStructure.NVIC_IRQChannelSubPriority = 3;		//子优先级3
	NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;			//IRQ通道使能
	NVIC_Init(&NVIC_InitStructure);	//根据指定的参数初始化VIC寄存器

   //USART 初始化设置

	USART_InitStructure.USART_BaudRate = bound;//串口波特率
	USART_InitStructure.USART_WordLength = USART_WordLength_8b;//字长为8位数据格式
	USART_InitStructure.USART_StopBits = USART_StopBits_1;//一个停止位
	USART_InitStructure.USART_Parity = USART_Parity_No;//无奇偶校验位
	USART_InitStructure.USART_HardwareFlowControl = USART_HardwareFlowControl_None;//无硬件数据流控制
	USART_InitStructure.USART_Mode = USART_Mode_Rx | USART_Mode_Tx;	//收发模式

  USART_Init(USART2, &USART_InitStructure); //初始化串口2
  USART_ITConfig(USART2, USART_IT_RXNE, ENABLE);//开启串口接受中断
  USART_Cmd(USART2, ENABLE);                    //使能串口2 

}

void USART2_IRQHandler(void)                	//串口2中断服务程序
	{
	u8 Res;
#if SYSTEM_SUPPORT_OS 		//如果SYSTEM_SUPPORT_OS为真，则需要支持OS.
	OSIntEnter();
#endif
	if(USART_GetITStatus(USART2, USART_IT_RXNE) != RESET)  //接收中断(接收到的数据必须是0x0d 0x0a结尾)
		{
		Res =USART_ReceiveData(USART2);	//读取接收到的数据

		if((USART_RX_STA&0x8000)==0)//接收未完成
			{
			if(USART_RX_STA&0x4000)//接收到了0x0d
				{
				if(Res!=0x0a)USART_RX_STA=0;//接收错误,重新开始
				else USART_RX_STA|=0x8000;	//接收完成了
				}
			else //还没收到0X0D
				{
				if(Res==0x0d)USART_RX_STA|=0x4000;
				else
					{
					USART_RX_BUF[USART_RX_STA&0X3FFF]=Res ;
					USART_RX_STA++;
					if(USART_RX_STA>(USART_REC_LEN-1))USART_RX_STA=0;//接收数据错误,重新开始接收
					}
				}
			}
     }