【米尔T113测评】开机点灯+TCP编程

giao LV 6

米尔电子的 MYD-YT113X 板卡由核心板 MYC-YT113X 和底板 MYB-YT113X 组成，核心板与底板采用邮票孔焊接方式。此外 MYIR 提供了丰富的软件资源以及文档资料。开发板在出厂时已经烧录了镜像，只需要按照手册上电即可使用。

系统以文件的形式为 LED 设备提供操作接口。这些接口位于/sys/class/leds 目录下。在硬件资源列表中，可以通过命令读写 sysfs 的方式对 LED 进行测试。其中 0 表示 LED 点亮，1 表示 LED 熄灭， None表示关闭心跳灯。现在以心跳灯 led-blue 为例测试 LED：

最后附上开发板点灯图：

TCP协议是一种面向连接的、可靠的、基于字节流的传输层通信协议。通讯过程如下：

服务器端先初始化Socket，然后与端口绑定(bind)，对端口进行监听(listen)，调用accept阻塞，等待客户端连接。在这时如果有个客户端初始化一个Socket，然后连接服务器(connect)，如果连接成功，这时客户端与服务器端的连接就建立了。客户端发送数据请求，服务器端接收请求并处理请求，然后把回应数据发送给客户端，客户端读取数据，最后关闭连接，一次交互结束。

服务端代码：

#include <stdio.h>
#include <stdlib.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <netinet/in.h>
#include <sys/socket.h>
#include <string.h>
#include <unistd.h>
#include <signal.h>
#include <sys/ipc.h>
#include <errno.h>
#include <sys/shm.h>
#include <time.h>
#include <pthread.h>
#include <arpa/inet.h>

#define BUFFER_SIZE     1024    // buf size
#define LISTENQ         1       // the max quote

#define SIZE_SHMADD 2048

int main(int argc, char *argv[]) {
    // check the arguments.
    if (argc != 2) {
        printf("Usage:\n");
        printf("    %s <port number>\n", argv[0]);
        return -1;
    }

    struct sockaddr_in server_addr;
    struct sockaddr_in client_addr;

    char recv_buf[BUFFER_SIZE];
    char send_buf[BUFFER_SIZE];

    pid_t pid;
    int sock_fd, conn_fd = -1;
    int optval = 1;
    int port = atoi(argv[1]);

    if ((sock_fd = socket(AF_INET, SOCK_STREAM, 0)) == -1) {
        perror("socket");
        return -1;
    }

    // setting bind port crycled.
    if ((setsockopt(sock_fd, SOL_SOCKET, SO_REUSEADDR,
                                    (void *)&optval, sizeof(int))) < 0) {
        perror("setsockopt");
        goto err;
    }

    // initized address.
    bzero(&server_addr, sizeof(struct sockaddr_in));
    server_addr.sin_family=AF_INET;
    server_addr.sin_addr.s_addr=htonl(INADDR_ANY);
    server_addr.sin_port = htons(port);

    // bind the port.
    if (bind(sock_fd, (struct sockaddr *)(&server_addr),
                                        sizeof(struct sockaddr)) == -1) {
        perror("bind");
        goto err;
    }
    
    // transform the socket into listen socket.
    if (listen(sock_fd, LISTENQ) == -1) {
        perror("listen");
        goto err;
    }

    printf("Waiting for client connectionn...\n");

    socklen_t cli_len = sizeof(struct sockaddr_in);
    conn_fd = accept(sock_fd, (struct sockaddr *)(&client_addr), &cli_len);
    if (conn_fd == -1) {
        perror("accept");
        close(sock_fd);
        return -1;
    }

    printf("Client accepted : %s:%d \n",
            inet_ntoa(client_addr.sin_addr), ntohs(client_addr.sin_port));

    pid = fork();
    if (pid > 0) {
        // The parent process is responsible for sending messages.
        while (1) {
            bzero(send_buf, sizeof(send_buf));
            char *str = fgets(send_buf, sizeof(send_buf), stdin);
            if (str == NULL) {
                perror("fgets");
                goto err;
            }

            if (send(conn_fd, send_buf, strlen(send_buf) - 1, 0) < 0) {
                perror("send");
                goto err;
            }
        } 
    }
    else if (pid == 0) {
        // The child process is responsible for receiving messages.
        while (1) {
            bzero(recv_buf, sizeof(recv_buf));
            if ((recv(conn_fd, recv_buf, BUFFER_SIZE, 0)) <= 0) {
                perror("recv");
                goto err;
            }

            printf("[Recv from client %s:%d] : %s\n",
                    inet_ntoa(server_addr.sin_addr),
                    htons(server_addr.sin_port),
                    recv_buf);
        }
    }
    else {
        perror("fork");
        goto err;
    }

    close(conn_fd);
    close(sock_fd);
    return 0;

err:
    close(conn_fd);
    close(sock_fd);
    return -1;
}

客户端代码

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <errno.h>
#include <sys/socket.h>
#include <sys/types.h>
#include <netinet/in.h>
#include <arpa/inet.h>

#define BUFFER_SIZE 1024

int main(int argc, char *argv[]) {
    // check the arguments.
    if (argc != 3) {
        printf("Usage:\n");
        printf("    %s <server addr> <port number>\n", argv[0]);
        return -1;
    }

    char *addr = argv[1];
    short port = atoi(argv[2]);

    int sock_fd;
    int ret;
    char recv_buf[BUFFER_SIZE], send_buf[BUFFER_SIZE];
    struct sockaddr_in server_addr;

    // initialize address/
    bzero(&server_addr, sizeof(server_addr));
    server_addr.sin_family = AF_INET;
    server_addr.sin_port = htons(port);
    server_addr.sin_addr.s_addr = inet_addr(addr);

    // create socket fd.
    sock_fd = socket(AF_INET, SOCK_STREAM, 0);
    if (sock_fd == -1) {
        perror("socket");
        return -1;
    }

    // connect.
    ret = connect(sock_fd, (struct sockaddr *)&server_addr, sizeof(struct sockaddr));
    if (ret == -1) {
        perror("connect");
        goto err;
    }

    printf("connect server(IP:%s Port: %d).\n", addr, port);

    pid_t pid = fork();
    if (pid > 0) {
        // The parent process is responsible for sending messages.
        while (1) {
            bzero(send_buf, sizeof(send_buf));
            char *str = fgets(send_buf, sizeof(send_buf), stdin);
            if (str == NULL) {
                perror("fgets");
                goto err;
            }

            if (send(sock_fd, send_buf, strlen(send_buf) - 1, 0) < 0) {
                perror("send");
                goto err;
            }
        }
    }
    else if (pid == 0) {
        // The child process is responsible for receiving messages.
        while (1) {
            bzero(recv_buf, sizeof(recv_buf));
            if (sock_fd > 0) {
                if ((recv(sock_fd, recv_buf, BUFFER_SIZE, 0)) <= 0) {
                    perror("recv");
                    goto err;
                }

                printf("[Recv from server %s:%d] : %s\n",
                        inet_ntoa(server_addr.sin_addr),
                        htons(server_addr.sin_port),
                        recv_buf);
            }
        }
    }
    else {
        perror("fork");
        goto err;
    }

    close(sock_fd);
    return 0;

err:
    close(sock_fd);
    return -1;
}

编译后运行结果如下：

服务端启起来，等待客户端连接。启动客户端，发送数据，服务端接收数据。

giao LV 6

udp --- 用户数据报协议，是一个无连接的简单的面向数据报的运输层协议。
udp不提供可靠性，它只是把应用程序传给IP层的数据报发送出去，但是并不能保证它们能到达目的地。
udp在传输数据报前不用在客户和服务器之间建立一个连接，且没有超时重发等机制，故而传输速度很快。
udp是一种面向无连接的协议，每个数据报都是一个独立的信息，包括完整的源地址或目的地址，它在网络上以任何可能的路径传往目的地，因此能否到达目的地，到达目的地的时间以及内容的正确性都是不能被保证的。

udp通讯流程很简单，具体步骤如下：

微信图片_20230908105059.png

udp服务端代码

#include <stdio.h>
#include <string.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <stdlib.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <stdbool.h>
#include <pthread.h>

#define BUFFER_SIZE 1024 // buf size

struct CONNECT_INFO {
    struct sockaddr_in client_addr;
};

static int sock_fd;
static volatile bool is_connect = false;

bool udp_server_init(short port) {
    struct sockaddr_in server_addr;

    sock_fd = socket(AF_INET, SOCK_DGRAM, 0);
    if (sock_fd == -1) {
        perror("socket");
        return false;
    }

    // initialize address.
    bzero(&server_addr, sizeof(server_addr));
    server_addr.sin_family = AF_INET;
    server_addr.sin_port = htons(port);
    server_addr.sin_addr.s_addr = htonl(INADDR_ANY);

    // bind the local port.
    if ((bind(sock_fd, (struct sockaddr *)&server_addr, 
                            sizeof(struct sockaddr_in))) == -1) {
        perror("bind");
        return false;
    }

    return true;
}

void *send_thread(void *arg) {
    struct CONNECT_INFO *info = (struct CONNECT_INFO *)arg;
    if (info == NULL) {
        printf("error connect info");
        return (void*)-1;
    }

    while (1) {
        char send_buf[BUFFER_SIZE];
        bzero(send_buf, sizeof(send_buf));

        // input from keyboard.
        char *str = fgets(send_buf, sizeof(send_buf), stdin);
        if (str == NULL) {
            perror("fgets");
            continue;
        }
        if (strlen(str) <= 1) {
            continue;
        }

        if(is_connect == false) {
            printf("No client are available!\n");
            continue;
        }

        // send data.
        if ((sendto(sock_fd, send_buf, strlen(str) - 1, 0,
                        (struct sockaddr *)&info->client_addr,
                        sizeof(struct sockaddr_in))) < 0) {
            perror("sendto");
            continue;
        }
    }

    return (void*)0;
}

int main(int argc, char *argv[]) {
    // check your input.
    if (argc != 2) {
        printf("Usage:\n");
        printf("    %s <port number>\n", argv[0]);
        return -1;
    }

    short port = atoi(argv[1]);

    bool ret = udp_server_init(port);
    if (ret == false) {
        goto err;
    }

    pthread_t t_id;
    struct CONNECT_INFO info;
    socklen_t addr_len = sizeof(struct sockaddr_in);

    memset(&info, 0, sizeof(info));

    pthread_create(&t_id, NULL, send_thread, (void *)&info);
    pthread_detach(t_id);

    printf("Waiting for client connectionn\n");
    while (1) {
        // recive from client.
        char recv_buf[BUFFER_SIZE];
        bzero(recv_buf, sizeof(recv_buf));
        if ((recvfrom(sock_fd, recv_buf, sizeof(recv_buf), 0,
                        (struct sockaddr *)&info.client_addr, &addr_len)) <= 0) {
            perror("recvfrom");
            goto err;
        }

        printf("[Recv from client %s:%d] : %s\n",
                inet_ntoa(info.client_addr.sin_addr),
                htons(info.client_addr.sin_port),
                recv_buf);
        
        is_connect = true;
    }

    close(sock_fd);
    return 0;

err:
    close(sock_fd);
    return -1;
}

udp客户端代码：

#include <stdio.h>
#include <string.h>
#include <netinet/in.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <stdlib.h>
#include <unistd.h>
#include <errno.h>
#include <arpa/inet.h>

#define BUFFER_SIZE 1024 // buf size

int main(int argc, char *argv[]) {
    // check the arguments.
    if (argc != 3) {
        printf("Usage:\n");
        printf("    %s <server_addr> <portnumber>\n", argv[0]);
        return -1;
    }

    int sock_fd;
    char send_buf[BUFFER_SIZE];
    char recv_buf[BUFFER_SIZE];
    struct sockaddr_in server_addr;

    char *addr = argv[1];
    short port = atoi(argv[2]);

    // initialize address.
    bzero(&server_addr, sizeof(server_addr));
    server_addr.sin_family = AF_INET;
    server_addr.sin_addr.s_addr = inet_addr(addr);
    server_addr.sin_port = htons(port);

    // create udp socket.
    sock_fd = socket(AF_INET, SOCK_DGRAM, 0);
    if (sock_fd == -1) {
        perror("socket");
        return -1;
    }

    pid_t pid = fork();
    if (pid > 0) {
        // The parent process is responsible for sending messages.
        while (1) {
            bzero(send_buf, sizeof(send_buf));    

            // read from stdin.
            char *str = fgets(send_buf, sizeof(send_buf), stdin);
            if (str == NULL) {
                perror("fgets");
                goto err;
            }
            if (strlen(str) <= 1) {
                continue;
            }

            // send data.
            if ((sendto(sock_fd, send_buf, strlen(str) - 1, 0,
                            (struct sockaddr *)&server_addr,
                            sizeof(struct sockaddr_in))) < 0) {
                perror("sendto");
                goto err;
            }
        }
    }
    else if (pid == 0) {
        // The child process is responsible for receiving messages.
        while (1) {
            bzero(recv_buf, sizeof(recv_buf));
            socklen_t addr_len = sizeof(struct sockaddr_in);
            if ((recvfrom(sock_fd, recv_buf, sizeof(recv_buf), 0,
                            (struct sockaddr *)&server_addr,
                            &addr_len)) <= 0) {
                perror("recvfrom");
                goto err;
            }

            printf("[Recv from server %s:%d] : %s\n",
                    inet_ntoa(server_addr.sin_addr),
                    htons(server_addr.sin_port),
                    recv_buf);
        }
    }

    close(sock_fd);
    return 0;

err:
    close(sock_fd);
    return -1;
}

编译后运行结果：