串口编程：
#define DEV_GPS_NAME "/dev/ttyS1"#define GPS_BAUD_RATE 9600int speed_arr[] = {B115200,B38400, B19200, B9600, B4800, B2400, B1200, B300, B38400, B19200, B9600, B4800, B2400, B1200, B300};int name_arr[] = {115200,38400, 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); printf("ispeed =%lu ospeed=%lu\r\n",cfgetispeed(&Opt),cfgetospeed(&Opt)); for ( i= 0; i < sizeof(speed_arr) / sizeof(int); i++) { if (speed == name_arr[i]) { printf("set_speed i =%d\r\n",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"); tcgetattr(fd, &Opt); printf("after ispeed =%lu ospeed=%lu\r\n",cfgetispeed(&Opt),cfgetospeed(&Opt)); return; } tcflush(fd,TCIOFLUSH); }}/*** 设置串口数据位，停止位和效验位*@param fd 类型 int 打开的串口文件句柄**@param databits 类型 int 数据位 取值 为 7 或者8**@param stopbits 类型 int 停止位 取值为 1 或者2**@param parity 类型 int 效验类型 取值为N,E,O,,S*/int set_Parity(int fd,int databits,int stopbits,int parity){ struct termios options; if ( tcgetattr( fd,&options) != 0) { perror("SetupSerial 1"); return -1; } printf("options flag %x\r\n", options.c_cflag); options.c_cflag &= ~CSIZE; switch (databits) /*设置数据位数*/ { case 7: options.c_cflag |= CS7; break; case 8: options.c_cflag |= CS8; break; default: fprintf(stderr,"Unsupported data size\n"); return -1; } 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); /* 设置为奇效验*/ options.c_iflag |= INPCK; /* Disnable parity checking */ break; case 'e': case 'E': options.c_cflag |= PARENB; /* Enable parity */ options.c_cflag &= ~PARODD; /* 转换为偶效验*/ 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 -1; } /* 设置停止位*/ switch (stopbits) { case 1: options.c_cflag &= ~CSTOPB; break; case 2: options.c_cflag |= CSTOPB; break; default: fprintf(stderr,"Unsupported stop bits\n"); return -1; } /* Set input parity option */ if (parity != 'n') options.c_iflag |= INPCK; options.c_cc[VTIME] = 150; // 15 seconds options.c_cc[VMIN] = 0; tcflush(fd,TCIFLUSH); /* Update the options and do it NOW TCIFLUSH*/ if (tcsetattr(fd,TCSANOW,&options) != 0) { perror("SetupSerial 3"); return -1; } printf("after options flag %x\r\n", options.c_cflag); return 0;}static int OpenAndSetGpsDev(void){ g_GpsFp = fopen(DEV_GPS_NAME,"r+"); if (NULL == g_GpsFp) { perror("Open ttyS1 failed!"); return -1; } g_GpsFd = fileno(g_GpsFp); if (g_GpsFd > 0) { set_speed(g_GpsFd,GPS_BAUD_RATE); } else { perror("Can't Open Serial Port!"); fclose(g_GpsFp); return -1; } if (set_Parity(g_GpsFd,8,1,'N') == -1) { perror("Set Parity Error"); fclose(g_GpsFp); g_GpsFd = 0; return -1; } return 0;}