I am using the SIM908 module to get GPS position.
The SIM908 sends the latitude and longitude in the ddmm.mmmm
format, but major online services for GPS location (for example, Google Earth) use the dd.dddd
format.
So, how can I modify my code to convert coordinates from the SIM908 to dd.dddd
format?
This is the SIM908 GSM Library Code that I am using:
#include "gps.h"
char GPSGSM::getBattInf(char *str_perc, char *str_vol)
{
char ret_val=0;
char *p_char;
char *p_char1;
gsm.SimpleWriteln("AT+CBC");
gsm.WaitResp(5000, 100, "OK");
if(gsm.IsStringReceived("+CBC"))
ret_val=1;
//BCL
p_char = strchr((char *)(gsm.comm_buf),',');
p_char1 = p_char+1; //we are on the first char of BCS
p_char = strchr((char *)(p_char1), ',');
if (p_char != NULL) {
*p_char = 0;
}
strcpy(str_perc, (char *)(p_char1));
//Voltage
p_char++;
p_char1 = strchr((char *)(p_char), '\r');
if (p_char1 != NULL) {
*p_char1 = 0;
}
strcpy(str_vol, (char *)(p_char));
return ret_val;
}
char GPSGSM::getBattTVol(char *str_vol)
{
char *p_char;
char *p_char1;
char ret_val=0;
gsm.SimpleWriteln("AT+CBTE?");
gsm.WaitResp(5000, 100, "OK");
if(gsm.IsStringReceived("+CBTE"))
ret_val=1;
//BCL
p_char = strchr((char *)(gsm.comm_buf),':');
p_char1 = p_char+2; //we are on the first char of BCS
p_char = strchr((char *)(p_char1), '\r');
if (p_char != NULL) {
*p_char = 0;
}
strcpy(str_vol, (char *)(p_char1));
return ret_val;
}
char GPSGSM::attachGPS()
{
if(AT_RESP_ERR_DIF_RESP == gsm.SendATCmdWaitResp("AT+CGPSPWR=1", 500, 100, "OK", 5))
return 0;
if(AT_RESP_ERR_DIF_RESP == gsm.SendATCmdWaitResp("AT+CGPSRST=1", 500, 100, "OK", 5))
return 0;
return 1;
}
char GPSGSM::deattachGPS()
{
if(AT_RESP_ERR_DIF_RESP == gsm.SendATCmdWaitResp("AT+CGPSPWR=0", 500, 100, "OK", 5))
return 0;
return 1;
}
char GPSGSM::getStat()
{
char ret_val=-1;
gsm.SimpleWriteln("AT+CGPSSTATUS?");
gsm.WaitResp(5000, 100, "OK");
if(gsm.IsStringReceived("Unknown")||gsm.IsStringReceived("unknown"))
ret_val=0;
else if(gsm.IsStringReceived("Not"))
ret_val=1;
else if(gsm.IsStringReceived("2D")||gsm.IsStringReceived("2d"))
ret_val=2;
else if(gsm.IsStringReceived("3D")||gsm.IsStringReceived("3d"))
ret_val=3;
return ret_val;
}
char GPSGSM::getPar(char *str_long, char *str_lat, char *str_alt, char *str_time, char *str_speed )
{
char ret_val=0;
char *p_char;
char *p_char1;
gsm.SimpleWriteln("AT+CGPSINF=0");
gsm.WaitResp(5000, 100, "OK");
if(gsm.IsStringReceived("OK"))
ret_val=1;
//longitude
p_char = strchr((char *)(gsm.comm_buf),',');
p_char1 = p_char+1; //we are on the first char of longitude
p_char = strchr((char *)(p_char1), ',');
if (p_char != NULL) {
*p_char = 0;
}
strcpy(str_long, (char *)(p_char1));
// latitude
p_char++;
p_char1 = strchr((char *)(p_char), ',');
if (p_char1 != NULL) {
*p_char1 = 0;
}
strcpy(str_lat, (char *)(p_char));
// altitude
p_char1++;
p_char = strchr((char *)(p_char1), ',');
if (p_char != NULL) {
*p_char = 0;
}
strcpy(str_alt, (char *)(p_char1));
// UTC time
p_char++;
p_char1 = strchr((char *)(p_char), ',');
if (p_char1 != NULL) {
*p_char1 = 0;
}
strcpy(str_time, (char *)(p_char));
// TTFF
p_char1++;
p_char = strchr((char *)(p_char1), ',');
if (p_char != NULL) {
*p_char = 0;
}
// num
p_char++;
p_char1 = strchr((char *)(p_char), ',');
if (p_char1 != NULL) {
*p_char1 = 0;
}
// speed
p_char1++;
p_char = strchr((char *)(p_char1), ',');
if (p_char != NULL) {
*p_char = 0;
}
strcpy(str_speed, (char *)(p_char1));
return ret_val;
}
void parseTime(char *field, int *time)
{
////////////////Time////////////
char tmp[4];
tmp[2]=0; // Init tmp and null terminate
tmp[0] = field[8];
tmp[1] = field[9];
time[0] = atoi(tmp); // Hours
tmp[0] = field[10];
tmp[1] = field[11];
time[1] = atoi(tmp); // Minutes
tmp[0] = field[12];
tmp[1] = field[13];
time[2] = atoi(tmp); // Seconds
/////////////Date///////////////
tmp[0] = field[0];
tmp[1] = field[1];
tmp[2] = field[2];
tmp[3] = field[3];
tmp[4]=0; // Init tmp and null terminate
time[3] = atoi(tmp); // year
tmp[0] = field[4];
tmp[1] = field[5];
tmp[2]=0; // Init tmp and null terminate
time[4] = atoi(tmp); // month
tmp[0] = field[6];
tmp[1] = field[7];
tmp[2]=0; // Init tmp and null terminate
time[5] = atoi(tmp); // day
}
// Read the latitude in decimal format from a GGA string
double convertLat(char* latString)
{
double latitude = atof(latString); // convert to a double (precise)
int deg = (int) latitude / 100; // extract the number of degrees
double min = latitude - (100 * deg); // work out the number of minutes
latitude = deg + (double) min/60.0; // convert to decimal format
return latitude;
}
// Read the longitude in decimal format from a GGA string
double convertLong(char* longString)
{
double longitude = atof(longString); // convert to a double
int deg = (int) longitude / 100; // extract the number of degrees
double min = longitude - (100 * deg); // work out the number of minutes
longitude = deg + (double) min/60.00; // convert to decimal format
return longitude;
}