Linux串口编程

之前一直在纠结这个怎么做，其实就是一个读写文件的流程，需要配置下串口的参数。

不过有意思的地方更在于，一，串口是可以作为终端的，linux终端tty是很有意思的，二，串口的配置涉及缓冲区设计，这点又和C语言的缓冲区息息相关，很多公司也喜欢考这样的C语言问题。

参考文献为：

http://www.ibm.com/developerworks/cn/linux/l-serials/index.html

http://book.51cto.com/art/200711/59766.htm#book_content

http://book.51cto.com/art/200711/59758.htm

其中，IBM的源码为：

#include<stdio.h>
#include<stdlib.h>
#include<unistd.h>
#include<sys/types.h>
#include<sys/stat.h>
#include<fcntl.h>
#include<termios.h>
#include<errno.h>

#define FALSE -1
#define TRUE 0

int speed_arr[] = { B38400, B19200, B9600, B4800, B2400, B1200, B300,B38400, B19200, B9600, B4800, B2400, B1200, B300, };
int name_arr[] = {38400,  19200,  9600,  4800,  2400,  1200,  300, 38400, 19200,  9600, 4800, 2400, 1200,  300, };
void set_speed(int fd, int speed){
int   i;
int   status;
struct termios   Opt;
tcgetattr(fd, &Opt);
for ( i= 0;  i < sizeof(speed_arr) / sizeof(int);  i++) {
if  (speed == name_arr[i]) {
tcflush(fd, TCIOFLUSH);
cfsetispeed(&Opt, speed_arr[i]);
cfsetospeed(&Opt, speed_arr[i]);
status = tcsetattr(fd, TCSANOW, &Opt);
if  (status != 0) {
perror("tcsetattr fd1");
return;
}
tcflush(fd,TCIOFLUSH);
}
}
}

int set_Parity(int fd,int databits,int stopbits,int parity)
{
struct termios options;
if  ( tcgetattr( fd,&options)  !=  0) {
perror("SetupSerial 1");
return(FALSE);
}
options.c_cflag &= ~CSIZE;
switch (databits)
{
case 7:
options.c_cflag |= CS7;
break;
case 8:
options.c_cflag |= CS8;
break;
default:
fprintf(stderr,"Unsupported data size\n"); return (FALSE);
}
switch (parity)
{
case 'n':
case 'N':
options.c_cflag &= ~PARENB;   /* Clear parity enable */
options.c_iflag &= ~INPCK;     /* Enable parity checking */
break;
case 'o':
case 'O':
options.c_cflag |= (PARODD | PARENB);
options.c_iflag |= INPCK;             /* Disnable parity checking */
break;
case 'e':
case 'E':
options.c_cflag |= PARENB;     /* Enable parity */
options.c_cflag &= ~PARODD;
options.c_iflag |= INPCK;       /* Disnable parity checking */
break;
case 'S':
case 's':  /*as no parity*/
options.c_cflag &= ~PARENB;
options.c_cflag &= ~CSTOPB;break;
default:
fprintf(stderr,"Unsupported parity\n");
return (FALSE);
}

switch (stopbits)
{
case 1:
options.c_cflag &= ~CSTOPB;
break;
case 2:
options.c_cflag |= CSTOPB;
break;
default:
fprintf(stderr,"Unsupported stop bits\n");
return (FALSE);
}
/* Set input parity option */
if (parity != 'n')
options.c_iflag |= INPCK;
tcflush(fd,TCIFLUSH);
options.c_cc[VTIME] = 150;
options.c_cc[VMIN] = 0; /* Update the options and do it NOW */
if (tcsetattr(fd,TCSANOW,&options) != 0)
{
perror("SetupSerial 3");
return (FALSE);
}
return (TRUE);
}

int main()
{
printf("STDIO COM1\n");
int fd;
fd = open("/dev/ttyS0",O_RDWR);
if(fd == -1)
{
perror("serialport error\n");
}
else
{
printf("open ");
printf("%s",ttyname(fd));
printf(" succesfully\n");
}

set_speed(fd,115200);
if (set_Parity(fd,8,1,'N') == FALSE)  {
printf("Set Parity Error\n");
exit (0);
}
char buf = 'c';
write(fd,&buf,1);
close(fd);
return 0;
}

51cto的这本书讲解较为详细，对每项参数有详细解释：

#include<stdio.h>
#include<stdlib.h>
#include<fcntl.h>
#include<unistd.h>
#include<errno.h>
#include<termios.h>
#include<sys/types.h>
#include<sys/stat.h>
int main()
{
printf("COM1 test program\n");
int fd;
fd = open("/dev/ttyS0",O_RDWR);
if(fd == -1)
{
perror("serialport error\n");
}
else{
printf("open %s succesfully\n", ttyname(fd));
}

struct termios Opt;
int status;

tcgetattr(fd, &Opt);
//set speed
cfsetispeed(&Opt, B115200);
cfsetospeed(&Opt, B115200);
//set databits
Opt.c_cflag &= ~CSIZE;
Opt.c_cflag |= CS8;
//set parity
Opt.c_cflag &= ~PARENB;
Opt.c_iflag &= ~INPCK;
//set stopbits
Opt.c_cflag &= ~CSTOPB;
tcsetattr(fd, TCSANOW, &Opt);
status = tcsetattr(fd, TCSANOW, &Opt);
if(status != 0)
{
perror("tcsetattr fd1");
return;
}

char buf = 'd';
write(fd, &buf, 1);
close(fd);

return 0;
}

原文地址：http://blog.csdn.net/bg2bkk/article/details/8623867