串口写AT命令

#include
#include
#include
#include

int fd;

int open_uart()
{
fd = open("/dev/ttyUSB2", O_RDWR|O_NOCTTY|O_NDELAY);
if(fd == -1)
{
perror("open tty fail");
return -1;
}
if(fcntl(fd, F_SETFL, 0)<0)
{
perror("open , fcntl fail");
return -1;
}
// printf("fcntl=%d\n", fcntl(fd, F_SETFL, 0));
// printf("fd is %d\n", fd);
/*
if(isatty(STDIN_FILENO))
{
printf("is a tty\n");
}
else
{
printf("not tty\n");
}
*/
return 0;
}

int set_uart()
{
struct termios options;

if(tcgetattr(fd, &options) != 0)
{
perror("get uart attr fail\n");
return -1;
}
cfsetispeed(&options, B19200);
cfsetospeed(&options, B19200);

options.c_cflag |= CLOCAL|CREAD;
options.c_cflag &= ~CRTSCTS;
options.c_cflag &= ~CSIZE;
options.c_cflag |= CS8;
options.c_cflag &= ~PARENB;
options.c_iflag &= ~INPCK;
options.c_cflag &= ~CSTOPB;
options.c_oflag &= ~OPOST;
options.c_cc[VTIME] = 1;
options.c_cc[VMIN] = 1;

tcflush(fd, TCIOFLUSH);

if(tcsetattr(fd, TCSANOW, &options) != 0)
{
perror("uart set attr fail");
return -1;
}

return 0;
}

int read_uart()
{
fd_set fs_read;
struct timeval time;

FD_ZERO(&fs_read);
FD_SET(fd, &fs_read);

_sec = 10;
_usec = 0;

while(select(fd+1, &fs_read, 0, 0, &time) > 0)
{
int len;
char buf[1024];

len=read(fd, buf, sizeof(buf));
printf("%s", buf);
}
}

int send_uart(char *str)
{
printf("send cmd:\t%s\n", str);
write(fd, str, strlen(str));
return 0;
}

int cmd_uart(char *str)
{
send_uart(str);
read_uart();
}

int main(int argc, char **argv)
{
char cmd_buf[1024];

open_uart();
set_uart();

cmd_uart("ate\r\n");
cmd_uart("ati\r\n");
cmd_uart("at+cimi\r\n");
cmd_uart("at+cmee=2\r\n");
cmd_uart("at+csq\r\n");
cmd_uart("at+creg=1\r\n");
cmd_uart("at+creg=?\r\n");
cmd_uart("at+creg?\r\n");
cmd_uart("at+cops?\r\n");

cmd_uart("at^hcsq\r\n");
cmd_uart("ag+cgdcont=1,\"ip\",\"3gnet\"\r\n");

while(fgets(cmd_buf, sizeof(cmd_buf), stdin))
{
strcat(cmd_buf, "\r\n");
cmd_uart(cmd_buf);
}

close(fd);

return 0;
}