判断linux+串口发送完成

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <fcntl.h>
#include <termios.h>

int main() {
    int fd;
    struct termios options;

    // 打开串口设备文件
    fd = open("/dev/ttyS0", O_RDWR | O_NOCTTY);
    if (fd == -1) {
        perror("open_port: Unable to open port");
        return -1;
    }

    // 获取当前串口参数
    tcgetattr(fd, &options);

    // 设置串口参数（波特率、数据位、停止位、奇偶校验等）
    cfsetispeed(&options, B9600);
    cfsetospeed(&options, B9600);
    options.c_cflag |= (CLOCAL | CREAD);
    options.c_cflag &= ~PARENB;
    options.c_cflag &= ~CSTOPB;
    options.c_cflag &= ~CSIZE;
    options.c_cflag |= CS8;

    // 应用新的串口参数
    tcsetattr(fd, TCSANOW, &options);

    // 发送数据
    const char *data = "Hello, Serial!";
    write(fd, data, strlen(data));

    // 等待数据发送完成
    tcdrain(fd);

    // 关闭串口设备文件
    close(fd);

    return 0;
}

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <fcntl.h>
#include <termios.h>
#include <sys/select.h>

int main() {
    int fd;
    struct termios options;
    fd_set writefds;

    // 打开串口设备文件
    fd = open("/dev/ttyS0", O_RDWR | O_NOCTTY);
    if (fd == -1) {
        perror("open_port: Unable to open port");
        return -1;
    }

    // 获取当前串口参数并设置
    tcgetattr(fd, &options);
    cfsetispeed(&options, B9600);
    cfsetospeed(&options, B9600);
    options.c_cflag |= (CLOCAL | CREAD);
    options.c_cflag &= ~PARENB;
    options.c_cflag &= ~CSTOPB;
    options.c_cflag &= ~CSIZE;
    options.c_cflag |= CS8;
    tcsetattr(fd, TCSANOW, &options);

    // 发送数据
    const char *data = "Hello, Serial!";
    write(fd, data, strlen(data));

    // 监控发送缓冲区
    FD_ZERO(&writefds);
    FD_SET(fd, &writefds);

    struct timeval timeout;
    timeout.tv_sec = 1; // 设置超时时间
    timeout.tv_usec = 0;

    int ret = select(fd + 1, NULL, &writefds, NULL, &timeout);
    if (ret == -1) {
        perror("select: Error");
    } else if (ret == 0) {
        printf("Timeout occurred! Data may not be fully sent.\n");
    } else {
        if (FD_ISSET(fd, &writefds)) {
            printf("Data has been sent successfully.\n");
        }
    }

    // 关闭串口设备文件
    close(fd);

    return 0;
}