初始化一个波特率为115200的串口。下面函数参数为115200.
代码如下：

void uart1_init(u32 bound)
{GPIO_InitTypeDef GPIO_InitStructure;USART_InitTypeDef USART_InitStructure;NVIC_InitTypeDef NVIC_InitStructure;RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_GPIOA, ENABLE);    //Enable the gpio clock //使能GPIO时钟RCC_APB2PeriphClockCmd(RCC_APB2Periph_USART1, ENABLE); //Enable the Usart clock //使能USART时钟GPIO_PinAFConfig(GPIOA,GPIO_PinSource9,GPIO_AF_USART1); GPIO_PinAFConfig(GPIOA,GPIO_PinSource10 ,GPIO_AF_USART1);        GPIO_InitStructure.GPIO_Pin = GPIO_Pin_9|GPIO_Pin_10;GPIO_InitStructure.GPIO_Mode=GPIO_Mode_AF;            //输出模式GPIO_InitStructure.GPIO_OType=GPIO_OType_PP;          //推挽输出GPIO_InitStructure.GPIO_Speed=GPIO_Speed_50MHz;       //高速50MHZGPIO_InitStructure.GPIO_PuPd=GPIO_PuPd_UP;            //上拉GPIO_Init(GPIOA, &GPIO_InitStructure);                            //初始化//UsartNVIC configuration //UsartNVIC配置NVIC_InitStructure.NVIC_IRQChannel = USART1_IRQn;//Preempt priority //抢占优先级NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority=1 ;//Subpriority //子优先级NVIC_InitStructure.NVIC_IRQChannelSubPriority = 0;              //Enable the IRQ channel //IRQ通道使能NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE; //Initialize the VIC register with the specified parameters //根据指定的参数初始化VIC寄存器 NVIC_Init(&NVIC_InitStructure); //USART Initialization Settings 初始化设置USART_InitStructure.USART_BaudRate = bound; //Port rate //串口波特率USART_InitStructure.USART_WordLength = USART_WordLength_8b; //The word length is 8 bit data format //字长为8位数据格式USART_InitStructure.USART_StopBits = USART_StopBits_1; //A stop bit //一个停止位USART_InitStructure.USART_Parity = USART_Parity_No; //Prosaic parity bits //无奇偶校验位USART_InitStructure.USART_HardwareFlowControl = USART_HardwareFlowControl_None; //No hardware data flow control //无硬件数>据流控制USART_InitStructure.USART_Mode = USART_Mode_Rx | USART_Mode_Tx; //Sending and receiving mode //收发模式USART_Init(USART1, &USART_InitStructure); //Initialize serial port 1 //初始化串口1USART_ITConfig(USART1, USART_IT_RXNE, ENABLE); //Open the serial port to accept interrupts //开启串口接受中断USART_Cmd(USART1, ENABLE);                     //Enable serial port 1 //使能串口1
}

RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_GPIOA, ENABLE); //Enable the gpio clock //使能GPIO时钟
RCC_APB2PeriphClockCmd(RCC_APB2Periph_USART1, ENABLE); //Enable the Usart clock //使能USART时钟
设置GPIO和uart时钟（我的理解是GPIO直接挂到AHB上，所以需要基于AHB总线使能对应GPIO时钟。uart控制器是挂到APB上，所以需要基于APB总线使能uart时钟）

GPIO_PinAFConfig(GPIOA,GPIO_PinSource9,GPIO_AF_USART1);
GPIO_PinAFConfig(GPIOA,GPIO_PinSource10 ,GPIO_AF_USART1);
将GPIOA的pin9、pin10配置成功能uart1。配置的寄存器为复用功能寄存器AFR

GPIO_InitStructure.GPIO_Pin = GPIO_Pin_9|GPIO_Pin_10;
GPIO_InitStructure.GPIO_Mode=GPIO_Mode_AF; //复用模式
GPIO_InitStructure.GPIO_OType=GPIO_OType_PP; //推挽输出
GPIO_InitStructure.GPIO_Speed=GPIO_Speed_50MHz; //高速50MHZ
GPIO_InitStructure.GPIO_PuPd=GPIO_PuPd_UP; //上拉
GPIO_Init(GPIOA, &GPIO_InitStructure); //初始化
对GPIO引脚进行配置，这个在GPIO端口配置部分有说明。

//UsartNVIC configuration //UsartNVIC配置
NVIC_InitStructure.NVIC_IRQChannel = USART1_IRQn; //Preempt priority //抢占优先级
NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority=1 ; //Subpriority //子优先级
NVIC_InitStructure.NVIC_IRQChannelSubPriority = 0; //Enable the IRQ channel //IRQ通道使能
NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE; //Initialize the VIC register with the specified parameters
//根据指定的参数初始化VIC寄存器
NVIC_Init(&NVIC_InitStructure);
1. 配置中断通道为USART1_IRQn。
2. 配置抢占中断优先级为1，这个值越小，中断优先级越高。
3. 配置响应中断优先级为0。
4. 使能uart1中断
说明：NVIC_PriorityGroupConfig(NVIC_PriorityGroup_4);优先级分组设置为group 4即4位抢占优先级即2^4种优先级（0-16），0位响应优先级。所以在设置时只有抢占优先级有效。

//USART Initialization Settings 初始化设置
USART_InitStructure.USART_BaudRate = bound; //Port rate //串口波特率
USART_InitStructure.USART_WordLength = USART_WordLength_8b; //The word length is 8 bit data format //字长为8位数据格式
USART_InitStructure.USART_StopBits = USART_StopBits_1; //A stop bit //一个停止位
USART_InitStructure.USART_Parity = USART_Parity_No; //Prosaic parity bits //无奇偶校验位
USART_InitStructure.USART_HardwareFlowControl = USART_HardwareFlowControl_None; //No hardware data flow control //无硬件数>据流控制
USART_InitStructure.USART_Mode = USART_Mode_Rx | USART_Mode_Tx; //Sending and receiving mode //收发模式
USART_Init(USART1, &USART_InitStructure); //Initialize serial port 1 //初始化串口1
USART_ITConfig(USART1, USART_IT_RXNE, ENABLE); //Open the serial port to accept interrupts //开启串口接受中断
USART_Cmd(USART1, ENABLE); //Enable serial port 1 //使能串口1
这个比较简单了，就是初始化串口，根据串口协议进行配置，打开中断，使能串口。