// this is a test about GPS Receiver
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <fcntl.h> // open() close()
#include <unistd.h> // read() write()
#include <termios.h> // set baud rate
#include <fcntl.h>
#include <sys/select.h>
#include <sys/time.h>
#include <sys/types.h>
#define DEVICE_TTYS "/dev/ttyS2"
#define BAUD_RATE_9600 B9600
#define FUNC_RUN 0
#define FUNC_NOT_RUN 1
#define ORG_GPS 1
#define SEL_GPGGA 2
#define SEL_GPGLL 3
#define SEL_GPGSA 4
#define SEL_GPGSV 5
#define SEL_GPRMC 6
#define SEL_GPVTG 7
#define FUNC_QUIT 8
//------------------------------------- read datas from GPS -------------------------------------------------
// succese return 1
// error return 0
int read_GPS_datas(int fd, char *rcv_buf)
{
int retval;
fd_set rfds;
struct timeval tv;
int ret,pos;
tv.tv_sec = 1;
tv.tv_usec = 0;
pos = 0; // point to rceeive buf
while (1)
{
FD_ZERO(&rfds);
FD_SET(fd, &rfds);
retval = select(fd+1 , &rfds, NULL, NULL, &tv);
if (retval == -1)
{
perror("select()");
break;
}
else if (retval)
{// pan duan shi fou hai you shu ju
ret = read(fd, rcv_buf+pos, 2048);
pos += ret;
if (rcv_buf[pos-2] == '\r' && rcv_buf[pos-1] == '\n')
{
FD_ZERO(&rfds);
FD_SET(fd, &rfds);
retval = select(fd+1 , &rfds, NULL, NULL, &tv);
if (!retval) break;// if no datas, break
}
}
else
{
printf("No data\n");
break;
}
}
return 1;
} // end read_GPS_datas
//------------------------------------- print ---------------------------------------------------------------
void print_prompt(void)
{
printf ("Select what you want to read:\n");
printf ("1 : Original GPS datas\n");
printf ("2 : GPGGA\n");
printf ("3 : GPGLL\n");
printf ("4 : GPGSA\n");
printf ("5 : GPGSV\n");
printf ("6 : GPRMC\n");
printf ("7 : GPVTG\n");
printf ("8 : Quit\n");
printf (">");
} // end print_prompt
//------------------------------------- FUNCTIONS ABOUT GPS -------------------------------------------------
//------------------------------------- FUNCTION 1 show all receive signal ----------------------------------
void GPS_original_signal(int fd)
{
char rcv_buf[2048];
while (1)
{
bzero(rcv_buf,sizeof(rcv_buf));
{
if (read_GPS_datas(fd,rcv_buf))
{
printf("%s",rcv_buf);
}
}
}
} // end GPS_original_signal
//------------------------------------- FUNCTION 2 resolve GPS GPGGA information ----------------------------
void GPS_resolve_gpgga(int fd)
{
} // end GPS_resolve_gpgga
//------------------------------------- FUNCTION 3 resolve GPS GPGLL information ----------------------------
void GPS_resolve_gpgll(int fd)
{
} // end GPS_resolve_gpgll
//------------------------------------- FUNCTION 4 resolve GPS GPGSA information ----------------------------
void GPS_resolve_gpgsa(int fd)
{
} // end GPS_resolve_gpgsa
//------------------------------------- FUNCTION 5 resolve GPS GPGSV information ----------------------------
void GPS_resolve_gpgsv(int fd)
{
} // end GPS_resolve_gpgsv
//------------------------------------- FUNCTION 6 resolve GPS GPRMC information ----------------------------
void GPS_resolve_gprmc(int fd)
{
} // end GPS_resolve_gprmc
//------------------------------------- FUNCTION 7 resolve GPS GPVTG information ----------------------------
void GPS_resolve_gpvtg(int fd)
{
} // end GPS_resolve_gpvtg
//------------------------------------- Receive GPS Signal --------------------------------------------------
void func_GPS(int fd)
{
int flag_func_run;
int flag_select_func;
ssize_t ret;
flag_func_run = FUNC_RUN;
while (flag_func_run == FUNC_RUN)
{
print_prompt(); // print select functions
scanf("%d",&flag_select_func); // user input select
getchar(); // get ENTER <LF>
switch(flag_select_func)
{
case ORG_GPS : {GPS_original_signal(fd); break; }
case SEL_GPGGA : {GPS_resolve_gpgga(fd); break; }
case SEL_GPGLL : {GPS_resolve_gpgll(fd); break; }
case SEL_GPGSA : {GPS_resolve_gpgsa(fd); break; }
case SEL_GPGSV : {GPS_resolve_gpgsv(fd); break; }
case SEL_GPRMC : {GPS_resolve_gprmc(fd); break; }
case SEL_GPVTG : {GPS_resolve_gpvtg(fd); break; }
case FUNC_QUIT :
{
flag_func_run = FUNC_NOT_RUN;
printf("Quit GPS function. byebye\n");
break;
}
default :
{
printf("please input your select use 1 to 8\n");
}
}
}
}// end func_GPS
//------------------------------------- init seriel port ---------------------------------------------------
void init_ttyS(int fd)
{
struct termios newtio;
bzero(&newtio, sizeof(newtio));
newtio.c_lflag &= ~(ECHO | ICANON);
newtio.c_cflag = B9600 | CS8 | CLOCAL | CREAD;
newtio.c_iflag = IGNPAR;
newtio.c_oflag = 0;
newtio.c_oflag &= ~(OPOST);
newtio.c_cc[VTIME] = 5; /* inter-character timer unused */
newtio.c_cc[VMIN] = 0; /* blocking read until 9 chars received */
tcflush(fd, TCIFLUSH);
tcsetattr(fd,TCSANOW,&newtio);
}//end init_ttyS
//------------------------------------- main ----------------------------------------------------------------
int main(void)
{
int fd;
printf ("\nThis is a test about GPS : receive GPS signal\n\n");
// open seriel port
fd = open(DEVICE_TTYS, O_RDONLY);
if (fd == -1)
{
printf("open device %s error\n",DEVICE_TTYS);
}
else
{
init_ttyS(fd); // init device
func_GPS(fd); // GPS functions
// close ttyS0
if (close(fd)!=0) printf("close device %s error",DEVICE_TTYS);
}
return 0;
} // end main
