serial-open.c

/*
stty -F /dev/ttyUSB0 38400 \
    clocal cread cs8 cstopb -parenb -crtscts \
    -ignbrk -brkint -parmrk -istrip -inlcr -igncr -icrnl -ixon \
    -echo -echonl -icanon -isig -iexten \
    -opost \
    min 1 time 1
*/

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

static int serial_open(const char *port, speed_t baud)
{
    int fd;
    struct termios tty;
    if ((fd = open(port, O_RDWR | O_NOCTTY | O_NONBLOCK)) < 0)
    {
        fprintf(stderr, "Failed to open port \"%s\"\n", port);
        return -1;
    }
    if (tcgetattr(fd, &tty) < 0)
    {
        fprintf(stderr, "Failed to tcgetattr of port \"%s\"\n", port);
        return -1;
    }
    cfsetospeed(&tty, baud);
    cfsetispeed(&tty, baud);
    tty.c_cflag |= (CLOCAL | CREAD);
    tty.c_cflag &= ~CSIZE;
    tty.c_cflag |= CS8;
    tty.c_cflag &= ~PARENB;
    tty.c_cflag |= CSTOPB;
    tty.c_cflag &= ~CRTSCTS;
    tty.c_iflag &= ~(IGNBRK | BRKINT | PARMRK | ISTRIP | INLCR | IGNCR | ICRNL | IXON);
    tty.c_lflag &= ~(ECHO | ECHONL | ICANON | ISIG | IEXTEN);
    tty.c_oflag &= ~OPOST;
    tty.c_cc[VMIN] = 1;
    tty.c_cc[VTIME] = 1;
    if (tcsetattr(fd, TCSANOW, &tty))
    {
        fprintf(stderr, "Failed to tcsetattr of port \"%s\"\n", port);
        return -1;
    }
    fprintf(stderr, "Port \"%s\" opened\n", port);
    return fd;
}