linux c语言串口通信

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

int open_serial_port(const char *portname) {
    int fd = open(portname, O_RDWR | O_NOCTTY | O_NDELAY);
    if (fd == -1) {
        perror("open_serial_port: Unable to open port");
        return -1;
    }
    return fd;
}

int set_serial_port(int fd, int baudrate, int bytesize, int parity, int stopbits) {
    struct termios options;
    tcgetattr(fd, &options);
    cfsetispeed(&options, baudrate);
    cfsetospeed(&options, baudrate);
    options.c_cflag |= (CLOCAL | CREAD);
    options.c_cflag &= ~PARENB;
    options.c_cflag &= ~CSTOPB;
    options.c_cflag &= ~CSIZE;
    switch (bytesize) {
        case 5: options.c_cflag |= CS5; break;
        case 6: options.c_cflag |= CS6; break;
        case 7: options.c_cflag |= CS7; break;
        case 8: options.c_cflag |= CS8; break;
    }
    switch (parity) {
        case 'n': options.c_cflag &= ~PARENB; break;
        case 'o': options.c_cflag |= (PARENB | PARODD); break;
        case 'e': options.c_cflag |= PARENB; options.c_cflag &= ~PARODD; break;
    }
    switch (stopbits) {
        case 1: options.c_cflag &= ~CSTOPB; break;
        case 2: options.c_cflag |= CSTOPB; break;
    }
    tcsetattr(fd, TCSANOW, &options);
    return 0;
}

int main() {
    int fd = open_serial_port("/dev/ttyS0");
    if (fd == -1) {
        return 1;
    }
    set_serial_port(fd, B9600, 8, 'n', 1);
    char buf[256];
    int n = read(fd, buf, sizeof(buf));
    if (n > 0) {
        printf("Received data: %s
", buf);
    }
    const char *data = "Hello, Serial Port!";
    write(fd, data, strlen(data));
    close(fd);
    return 0;
}