串口编程（例子）

//设置串口：

int set_opt(int fd,int nSpeed, int nBits, char nEvent, intnStop)

{

struct termios newtio,oldtio;

if ( tcgetattr( fd,&oldtio) != 0) {

perror("SetupSerial 1");

return -1;

}

bzero( &newtio, sizeof( newtio ) );

newtio.c_cflag |= CLOCAL | CREAD;

newtio.c_cflag &= ~CSIZE;

switch( nBits )

{

case 7:

newtio.c_cflag |= CS7;

break;

case 8:

newtio.c_cflag |= CS8;

break;

}

switch( nEvent )

{

case 'O': //奇数

newtio.c_cflag |= PARENB;

newtio.c_cflag |= PARODD;

newtio.c_iflag |= (INPCK | ISTRIP);

break;

case 'E': //偶数

newtio.c_iflag |= (INPCK | ISTRIP);

newtio.c_cflag |= PARENB;

newtio.c_cflag &= ~PARODD;

break;

case 'N': //无奇偶校验位

newtio.c_cflag &= ~PARENB;

break;

}

switch( nSpeed )

{

case 2400:

cfsetispeed(&newtio, B2400);

cfsetospeed(&newtio, B2400);

break;

case 4800:

cfsetispeed(&newtio, B4800);

cfsetospeed(&newtio, B4800);

break;

case 9600:

cfsetispeed(&newtio, B9600);

cfsetospeed(&newtio, B9600);

break;

case 115200:

cfsetispeed(&newtio, B115200);

cfsetospeed(&newtio, B115200);

break;

case 460800:

cfsetispeed(&newtio, B460800);

cfsetospeed(&newtio, B460800);

break;

default:

cfsetispeed(&newtio, B9600);

cfsetospeed(&newtio, B9600);

break;

}

if( nStop == 1 )

newtio.c_cflag &= ~CSTOPB;

else if ( nStop == 2 )

newtio.c_cflag |= CSTOPB;

newtio.c_cc[VTIME] = 0;

newtio.c_cc[VMIN] = 0;

tcflush(fd,TCIFLUSH);

if((tcsetattr(fd,TCSANOW,&newtio))!=0)

{

perror("com set error");

return -1;

}

printf("set done!\n");

return 0;

}

int open_port(int fd,int comport)

{

char *dev[]={"/dev/ttyS0","/dev/ttyS1","/dev/ttyS2"};

long vdisable;

if (comport==1)//串口 1

{

fd = open( "/dev/ttyS0", O_RDWR|O_NOCTTY|O_NDELAY);

if (-1 == fd){

perror("Can't Open Serial Port");

return(-1);

}

}

else if(comport==2)//串口 2

{

fd = open( "/dev/ttyS1", O_RDWR|O_NOCTTY|O_NDELAY);

if (-1 == fd){

perror("Can't Open Serial Port");

return(-1);

}

}

else if (comport==3)//串口 3

{

fd = open( "/dev/ttyS2", O_RDWR|O_NOCTTY|O_NDELAY);

if (-1 == fd){

perror("Can't Open Serial Port");

return(-1);

}

}

if(fcntl(fd, F_SETFL, 0)<0)

printf("fcntl failed!\n");

else

printf("fcntl=%d\n",fcntl(fd, F_SETFL,0));

if(isatty(STDIN_FILENO)==0)

printf("standard input is not a terminal device\n");

else

printf("isatty success!\n");

printf("fd-open=%d\n",fd);

return fd;

}

#include

#include

#include

#include

#include

#include

#include

#include

#include

int main(void)

{

int fd;

int nread,i;

char buff[]="Hello\n";

if((fd=open_port(fd,1))<0){//打开串口

perror("open_port error");

return;

}

if((i=set_opt(fd,115200,8,'N',1))<0){//设置串口

perror("set_opt error");

return;

}

printf("fd=%d\n",fd);

fd=3;

nread=read(fd,buff,8);//读串口

printf("nread=%d,%s\n",nread,buff);

close(fd);

return;

}