Linux串口应用编程-RZMPU工业控制教程连载（6）

/* * ./serial_send_recv  */ int main(int argc, char **argv){ int fd; int iRet; char c;
 /* 1. open */
 /* 2. setup* 115200,8N1 * RAW mode * return data immediately*/
 /* 3. write and read */
 if (argc != 2) { printf("Usage: \n");printf("%s \n", argv[0]); return -1; }
 fd = open_port(argv[1]); if (fd < 0) {printf("open %s err!\n", argv[1]);return -1; }
 iRet = set_opt(fd, 115200, 8, 'N', 1); if (iRet) { printf("set port err!\n"); return -1; }

printf("Enter a char: ");while (1) {scanf("%c", &c); iRet = write(fd, &c, 1);iRet = read(fd, &c, 1); if (iRet == 1)printf("get: %02x %c\n", c, c); elseprintf("can not get data\n");}

int open_port(char *com){int fd;//fd = open(com, O_RDWR|O_NOCTTY|O_NDELAY); fd = open(com, O_RDWR|O_NOCTTY); if (-1 == fd){return(-1); }
//if(fcntl(fd, F_SETFL, 0)<0) /* 设置串口 Flag *///{ // printf("fcntl failed!\n"); // return -1;//}
 return fd; }

 /* set_opt(fd,115200,8,'N',1) */ 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;
 newtio.c_lflag &= ~(ICANON | ECHO | ECHOE | ISIG); /*Input*/ newtio.c_oflag &= ~OPOST; /*Output*/
 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;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[VMIN] = 1; /* 读数据时的最小字节数: 没读到这些数据我就不返回! */newtio.c_cc[VTIME] = 0; /* 等待第 1 个数据的时间: * 比如 VMIN 设为 10 表示至少读到 10 个数据才返回, * 但是没有数据总不能一直等吧? 可以设置 VTIME(单位是 10 秒) * 假设 VTIME=1，表示: * 10 秒内一个数据都没有的话就返回 * 如果 10 秒内至少读到了 1 个字节，那就继续等待，完全读到VMIN 个数据再返回 */
 tcflush(fd,TCIFLUSH);
 if((tcsetattr(fd,TCSANOW,&newtio))!=0) { perror("com set error"); return -1; } //printf("set done!\n"); return 0; }

$ source /opt/remi-sdk/environment-setup-aarch64-poky-linux$ $CC -o serial_send_recv serial_send_recv.c$ scp serial_send_recv root@192.168.5.9:/home/root

# cd /home/root/# ./serial_send_recv /dev/ttySC4Enter a char: 1get: 31 1get: 0a2get: 32 2get: 0a

$GPGGA，<1>，<2>，<3>，<4>，<5>，<6>，<7>，<8>，<9>，M，<10>，M，<11>，<12>*hh

 while (1) { /* eg. $GPGGA,082559.00,4005.22599,N,11632.58234,E,1,04,3.08,14.6,M,-5.6,M,,*76"*/ /* read line */ iRet = read_gps_raw_data(fd, buf);
 /* parse line */ if (iRet == 0) {iRet = parse_gps_raw_data(buf, time, Lat, ns, Lng, ew); }
 /* printf */ if (iRet == 0) { printf("Time : %s\n", time); printf("ns : %s\n", ns); printf("ew : %s\n", ew); printf("Lat : %s\n", Lat); printf("Lng : %s\n", Lng);
 /* 纬度格式: ddmm.mmmm */ sscanf(Lat+2, "%f", &fLat); fLat = fLat / 60; fLat += (Lat[0] - '0')*10 + (Lat[1] - '0');
 /* 经度格式: dddmm.mmmm */ sscanf(Lng+3, "%f", &fLng); fLng = fLng / 60; fLng += (Lng[0] - '0')*100 + (Lng[1] - '0')*10 + (Lng[2] - '0'); printf("Lng,Lat: %.06f,%.06f\n", fLng, fLat); } }

 int read_gps_raw_data(int fd, char *buf){ int i = 0;int iRet; char c; int start = 0;
 while (1) {iRet = read(fd, &c, 1); if (iRet == 1) {if (c == '$')start = 1; if (start){ buf[i++] = c; } if (c == '\n' || c == '\r') return 0; }else { return -1; } } }

 /* eg. $GPGGA,082559.00,4005.22599,N,11632.58234,E,1,04,3.08,14.6,M,-5.6,M,,*76" */ int parse_gps_raw_data(char *buf, char *time, char *lat, char *ns, char *lng, char *ew){ char tmp[10];
 if (buf[0] != '$') return -1; else if (strncmp(buf+3, "GGA", 3) != 0) return -1; else if (strstr(buf, ",,,,,")) { printf("Place the GPS to open area\n");
 return -1; } else { //printf("raw data: %s\n", buf); sscanf(buf, "%[^,],%[^,],%[^,],%[^,],%[^,],%[^,]", tmp, time, lat, ns,lng, ew);return 0;} }

$ source /opt/remi-sdk/environment-setup-aarch64-poky-linux$ $CC -o gps_read gps_read.c$ scp gps_read root@192.168.5.9:/home/root

# cd /home/root/# ./gps_read /dev/ttySC4