linux 串口 发送 阻塞

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

int main() {
    int fd = open("/dev/ttyS0", O_RDWR | O_NOCTTY | O_NONBLOCK);
    if (fd == -1) {
        perror("open_port: Unable to open /dev/ttyS0");
        return -1;
    }

    struct termios options;
    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);

    struct timeval timeout;
    timeout.tv_sec = 5;
    timeout.tv_usec = 0;
    setsockopt(fd, SOL_SOCKET, SO_SNDTIMEO, (char *)&timeout, sizeof(timeout));

    const char *message = "Hello, Serial Port!";
    int len = strlen(message);
    int bytes_sent = write(fd, message, len);

    if (bytes_sent == -1) {
        perror("write");
    } else {
        printf("Sent %d bytes to serial port\n", bytes_sent);
    }

    close(fd);
    return 0;
}