main.c

自己写的gps信息解码的程序

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

//
#define UInt32     unsigned int
#define Int16      short
#define UInt16     unsigned short
#define UInt8      unsigned char
#define Boolean    int

#define false      0
#define true       1

#define GPS_RECV_CMD_MAX_BUF 256 //the buffer size


//the gga info struct

typedef struct GGAINFO{
	int    bIsGPGGA;                 
	UInt8  hour, bjhour, min, sec, secFrac; 
	double latitude;                
	UInt8  latNS;                  
	double longitude;              
	UInt8  lgtEW;                
	//	UInt8  hour, bjhour, min, sec, secFrac; 
	UInt8  satellites;              
	Int16  altitude;        
	//	UInt8  altUnit;               
}GGAINFO;

int main(void)
{
	int fd;
	int i;
	char buffer[GPS_RECV_CMD_MAX_BUF];//receive buffer
	char tmp;

	GGAINFO ggainfo;

	char Degree[4];
	char Minute[8];

	char Hour[4];
	char Minu[4];
	char Second[4];

	char Satnum[4];

	int no = 0;

	//open the COM
	if((fd=open_port(fd,4))<0)
	{
		perror("open_port error");
		return;
	}
	printf("fd=%d\n",fd);

	//set the COM
	if((i=set_opt(fd,9600,8,'N',1))<0)
	{
		perror("set_opt error");
		return;
	}

	// 
	while(1)
	{
		while(!Is_startGP(fd));
//		printf("start to receive\n");


		//receive the info
		for(i = 0; i<GPS_RECV_CMD_MAX_BUF;i++) 
		{
			read(fd,&tmp,1);
			buffer[i]=tmp;
//			printf("%c",buffer[i]);
			if(tmp=='\n')break;
		}
//		printf("\n");

		//proc the GGA info

		if(Is_GGA(buffer))
		{
			ggainfo.bIsGPGGA = 1;

			//Time:6-15
			no = 6;
			for(i = 0;i < 4;i++)
				Hour[i]=0;
			Hour[0]=buffer[no];
			Hour[1]=buffer[no+1];


			no += 2;
			for(i = 0;i < 4;i++)
				Minu[i]=0;
			Minu[0]=buffer[no];
			Minu[1]=buffer[no+1];

			no += 2;
			for(i = 0;i < 4;i++)
				Second[i]=0;
			Second[0]=buffer[no];
			Second[1]=buffer[no+1];

			ggainfo.hour = atoi(Hour);
			ggainfo.min = atoi(Minu);
			ggainfo.sec = atoi(Second);
			ggainfo.secFrac = 0;

			ggainfo.bjhour = ggainfo.hour + 8;
			if(ggainfo.bjhour > 24)
				ggainfo.bjhour -=  24;


			//Latitude:17-25
			no = 17;
			for(i = 0;i < 4;i++)
				Degree[i]=0;
			Degree[0]=buffer[no];
			Degree[1]=buffer[no+1];

			no+=2;
			for(i=0;i<8;i++)
				Minute[i]=0;
			for(i=0;i<7;i++)
				Minute[i]=buffer[no+i];
			//	int l=atoi(Degree);
			ggainfo.latitude=(atof(Minute)) / 60.0 + atoi(Degree);


			//NS:27
			ggainfo.latNS = buffer[27];


			//Longitude:29-38
			no = 29;
			for(i=0;i<4;i++)
				Degree[i]=0;
			Degree[0]=buffer[no];
			Degree[1]=buffer[no+1];
			Degree[2]=buffer[no+2];
			no+=3;
			for(i=0;i<8;i++)	   
				Minute[i]=0;
			for(i=0;i<7;i++)
				Minute[i]=buffer[no+i];
			//	int B=atoi(Degree);
			ggainfo.longitude=(atof(Minute)) / 60.0 + atoi(Degree);

			//WE:40
			ggainfo.lgtEW = buffer[40];


			//the number of satellite:44-45
			no = 44;
			for(i = 0;i < 4;i++)
				Satnum[i]=0;
			Satnum[0]=buffer[no];
			Satnum[1]=buffer[no+1];
			ggainfo.satellites = atoi(Satnum);


			printf("UTC Time:%d h %d m %d s\n",ggainfo.hour,ggainfo.min,ggainfo.sec);
			printf("BJ Time:%d h %d m %d s\n",ggainfo.bjhour,ggainfo.min,ggainfo.sec); 
			printf("Latitude:%c wei %f \n",ggainfo.latNS,ggainfo.latitude);
			printf("Longitude:%c jing %f \n",ggainfo.lgtEW,ggainfo.longitude);
			printf("Satellites:%d \n",ggainfo.satellites);
			printf("\n");

		}
		else continue;
		sleep(1);
	}
	close(fd);
	return 0;
}



int Is_startGP(int fp)
{
	int status=0;
	char cc,tmp;
	read(fp,&cc,1);
	tmp=cc;
	if(tmp=='$')status=1;
	return status;
}



int Is_GGA(char p[GPS_RECV_CMD_MAX_BUF])
{
	int status=0;
	if(p[2] == 'G' && p[3] == 'G' && p[4] == 'A')
		status=1;
	return status;
}