波特率设置示例：

struct termios options;/** Get the current options for the port...*/
tcgetattr(fd, &options);
/** Set the baud rates to 19200...*/
cfsetispeed(&options, B19200);
cfsetospeed(&options, B19200);/** Enable the receiver and set local mode...*/
options.c_cflag |= (CLOCAL | CREAD);/** Set the new options for the port...*/
tcsetattr(fd, TCSANOW, &options);

“ 常量TCSANOW标志所有改变必须立刻生效而不用等到数据传输结束.其他另一些常数可以保证等待数据结束或者刷新输入输出之后再生效.”

#include<stdio.h>
#include<stdlib.h>
#include<string.h>
#include<sys/types.h>
#include<sys/stat.h>
#include<fcntl.h>
#include<unistd.h>
#include<termios.h>
#include<string.h>
typedef struct _tim
{int hh;int mm;float ss;
}tim;
typedef struct _addr
{int dd;float mm;char pos;
}addr;
typedef struct _date
{int year;int month;int day;
}date;
int set_opt(int fd,int nSpeed, int nBits, char nEvent, int nStop)
{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':newtio.c_cflag |= PARENB;newtio.c_cflag |= PARODD;newtio.c_iflag |= (INPCK | ISTRIP);break;case 'E': newtio.c_iflag |= (INPCK | ISTRIP);newtio.c_cflag |= PARENB;newtio.c_cflag &= ~PARODD;break;case 'N':  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;//重要newtio.c_cc[VMIN] = 0;//返回的最小值  重要tcflush(fd,TCIFLUSH);if((tcsetattr(fd,TCSANOW,&newtio))!=0){perror("com set error");return -1;}
//  printf("set done!\n\r");return 0;
}
void analyser(char buf[]);
int main(void)
{int fd1,nset1,nread;char buf[1024];fd1 = open("/dev/ttyS1", O_RDWR|O_NOCTTY|O_NDELAY);//打开串口if (fd1 == -1)exit(1);nset1 = set_opt(fd1,4800, 8, 'N', 1);//设置串口属性if (nset1 == -1)exit(1);while (1){memset(buf,0,1024); nread = read(fd1, buf, 1024);//读串口if (nread > 0){// printf("\n GPS DATALen=%d\n",nread); buf[nread] = '\0';// printf( "GPS %s\n", buf); //输出所读数据break;}sleep(2);//睡眠，等待数据多一点}close(fd1);analyser(buf);return 0;
}void analyser(char buf[1024])
{char *new_buf;tim cur_time;addr cur_lat;addr cur_lng;date cur_date;float speed;float heading;char is;new_buf = strstr(buf, "RMC");new_buf += 4;sscanf(new_buf, "%2d%2d%f,%c,%2d%f,%c,%3d%f,%c,%f,%f,%2d%2d%2d",\
&cur_time.hh,&cur_time.mm,&cur_time.ss,\
&is,\
&cur_lat.dd,&cur_lat.mm,&cur_lat.pos,\
&cur_lng.dd,&cur_lng.mm,&cur_lng.pos,\
&speed,&heading,\
&cur_date.day,&cur_date.month,&cur_date.year);printf("当前时间:%d时%d分%.2f秒\n", cur_time.hh, cur_time.mm, cur_time.ss);printf("当前位置:%s %d度%.4f分, %s %d度%.4f分\n", cur_lat.pos == 'N'?"北纬":"南纬", cur_lat.dd, cur_lat.mm\,cur_lng.pos == 'E'?"东经":"西经", cur_lng.dd, cur_lng.mm);printf("当前日期:20%d年%d月%d日\n", cur_date.year, cur_date.month, cur_date.day);}