用keil 5写一个两个串口互相接收发送的程序

以下是基于Keil 5的两个串口互相接收发送的程序示例：

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include "stm32f4xx.h"

#define BUF_SIZE 64

char str1[BUF_SIZE] = {0};
char str2[BUF_SIZE] = {0};

void USART1_Init(void);
void USART2_Init(void);
void USART1_Send(char *str);
void USART2_Send(char *str);

int main(void)
{
    USART1_Init();
    USART2_Init();

    while (1)
    {
        // 从串口1接收数据
        if (USART_GetFlagStatus(USART1, USART_FLAG_RXNE) == SET)
        {
            char ch = USART_ReceiveData(USART1);
            if (ch == '\r' || ch == '\n')
            {
                USART_SendData(USART2, '\r');
                USART_SendData(USART2, '\n');
                USART2_Send(str1);
                memset(str1, 0, BUF_SIZE);
            }
            else
            {
                strncat(str1, &ch, 1);
            }
        }

        // 从串口2接收数据
        if (USART_GetFlagStatus(USART2, USART_FLAG_RXNE) == SET)
        {
            char ch = USART_ReceiveData(USART2);
            if (ch == '\r' || ch == '\n')
            {
                USART_SendData(USART1, '\r');
                USART_SendData(USART1, '\n');
                USART1_Send(str2);
                memset(str2, 0, BUF_SIZE);
            }
            else
            {
                strncat(str2, &ch, 1);
            }
        }
    }
}

void USART1_Init(void)
{
    GPIO_InitTypeDef GPIO_InitStructure;
    USART_InitTypeDef USART_InitStructure;

    RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_GPIOA, ENABLE);
    RCC_APB2PeriphClockCmd(RCC_APB2Periph_USART1, ENABLE);

    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;
    GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
    GPIO_InitStructure.GPIO_OType = GPIO_OType_PP;
    GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_UP;
    GPIO_Init(GPIOA, &GPIO_InitStructure);

    USART_InitStructure.USART_BaudRate = 115200;
    USART_InitStructure.USART_WordLength = USART_WordLength_8b;
    USART_InitStructure.USART_StopBits = USART_StopBits_1;
    USART_InitStructure.USART_Parity = USART_Parity_No;
    USART_InitStructure.USART_HardwareFlowControl = USART_HardwareFlowControl_None;
    USART_InitStructure.USART_Mode = USART_Mode_Rx | USART_Mode_Tx;
    USART_Init(USART1, &USART_InitStructure);

    USART_Cmd(USART1, ENABLE);
}

void USART2_Init(void)
{
    GPIO_InitTypeDef GPIO_InitStructure;
    USART_InitTypeDef USART_InitStructure;

    RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_GPIOA, ENABLE);
    RCC_APB1PeriphClockCmd(RCC_APB1Periph_USART2, ENABLE);

    GPIO_PinAFConfig(GPIOA, GPIO_PinSource2, GPIO_AF_USART2);
    GPIO_PinAFConfig(GPIOA, GPIO_PinSource3, GPIO_AF_USART2);

    GPIO_InitStructure.GPIO_Pin = GPIO_Pin_2 | GPIO_Pin_3;
    GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF;
    GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
    GPIO_InitStructure.GPIO_OType = GPIO_OType_PP;
    GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_UP;
    GPIO_Init(GPIOA, &GPIO_InitStructure);

    USART_InitStructure.USART_BaudRate = 115200;
    USART_InitStructure.USART_WordLength = USART_WordLength_8b;
    USART_InitStructure.USART_StopBits = USART_StopBits_1;
    USART_InitStructure.USART_Parity = USART_Parity_No;
    USART_InitStructure.USART_HardwareFlowControl = USART_HardwareFlowControl_None;
    USART_InitStructure.USART_Mode = USART_Mode_Rx | USART_Mode_Tx;
    USART_Init(USART2, &USART_InitStructure);

    USART_Cmd(USART2, ENABLE);
}

void USART1_Send(char *str)
{
    while (*str)
    {
        while (USART_GetFlagStatus(USART1, USART_FLAG_TC) == RESET);
        USART_SendData(USART1, *str++);
    }
}

void USART2_Send(char *str)
{
    while (*str)
    {
        while (USART_GetFlagStatus(USART2, USART_FLAG_TC) == RESET);
        USART_SendData(USART2, *str++);
    }
}

这个程序使用了两个串口：USART1 和 USART2。在主循环中，程序不断轮询两个串口的接收标志位，如果有数据接收，则将数据存储在缓冲区中。当接收到回车或换行符时，将缓冲区中的数据发送到另一个串口，并清空缓冲区。

注意：在使用 Keil 5 编写 STM32 代码时，需要根据具体的芯片型号选择正确的库文件。本示例代码中使用的是 STM32F407VG 的库文件。如果使用其他型号的芯片，需要修改库文件路径和包含的头文件。