linux串口接收数据超时

stty -F /dev/ttyS0 9600 cs8 -cstopb -parenb

cat /dev/ttyS0

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

int main() {
    int fd = open("/dev/ttyS0", O_RDWR | O_NOCTTY | O_NDELAY);
    if (fd == -1) {
        perror("Unable to open serial port");
        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);

    char buffer[256];
    while (1) {
        int n = read(fd, buffer, sizeof(buffer));
        if (n > 0) {
            buffer[n] = '\0';
            printf("%s", buffer);
        }
    }

    close(fd);
    return 0;
}

sudo apt-get install minicom
minicom -D /dev/ttyS0 -b 9600