如何去实现stm32 USART串口的程序代码呢

usart.c

#include "usart.h"

void USART1_Init(u32 baud)
{
    GPIO_InitTypeDef GPIO_InitStructure;
    USART_InitTypeDef USART_InitStructure;
    NVIC_InitTypeDef NVIC_InitStructure;
    //1*开启串口1时钟和其连接的引脚时钟
    RCC_APB2PeriphClockCmd(RCC_APB2Periph_USART1,ENABLE);
    RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOA,ENABLE);
   
    //2*配置引脚输入输出结构体
    GPIO_InitStructure.GPIO_Pin = GPIO_Pin_9;
    GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
    GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF_PP;
    GPIO_Init(GPIOA,&GPIO_InitStructure);
   
    GPIO_InitStructure.GPIO_Pin = GPIO_Pin_10;
    GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
    GPIO_InitStructure.GPIO_Mode = GPIO_Mode_IN_FLOATING;
    GPIO_Init(GPIOA,&GPIO_InitStructure);
   
    //3*配置串口
    USART_InitStructure.USART_BaudRate = baud; //波特率设置
    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_Mode = USART_Mode_Rx|USART_Mode_Tx;   //收发模式
    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_Init(USART1,&USART_InitStructure);
   
    //4*打开串口使能
    USART_Cmd(USART1,ENABLE);
    USART_ClearFlag(USART1, USART_FLAG_TC);  //清除发送标志位
   
    //5*设置串口中断类型
    USART_ITConfig(USART1,USART_IT_RXNE,ENABLE);
   
    //6*配置中断优先级
    NVIC_InitStructure.NVIC_IRQChannel =USART1_IRQn;
    NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 3;
    NVIC_InitStructure.NVIC_IRQChannelSubPriority = 3;
    NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE ;   
    NVIC_Init(&NVIC_InitStructure);
}

void USART1_IRQHandler()
{
    u8 r;
    if(USART_GetITStatus(USART1,USART_IT_RXNE)==1)
    {
        r = USART_ReceiveData(USART1);
        USART_SendData(USART1,r);
        while(USART_GetFlagStatus(USART1,USART_FLAG_TC)!=1); //没有开启中断只是获取状态标志
    }
    USART_ClearFlag(USART1,USART_FLAG_TC);
}
usart.h


#ifndef _usart_H
#define _usart_H


#include "system.h"
void USART1_Init(u32 baud);


#endif

main.c


#include "systick.h"
#include "led.h"
#include "system.h"
#include "usart.h"

int main()
{
    u8 i;
    SysTick_Init(72);  //系统时钟初始
    LED_INIT();
    NVIC_PriorityGroupConfig(NVIC_PriorityGroup_2);
    USART1_Init(9600);
    while(1)
    {
        i++;
        if(i%20==0)
        {
            led1=!led1;
        }
        delay_ms(10);
    }
}