How to extract latitude and longitude from GPS

Question

I want to extract longitude and latitude from GSM/GPS module and then upload it to thingspeak. I am using sim808 GSM/GPS module and AT+CGPSINF=0 to get GPS location information sentence (CGPSINF: 0,6.823375,80.001038,36.300000,20170705124133.000,0,10,0.037040,47.410000 ). I want to extract longitude and latitude from it. Does anyone know how to do it? I am not an expert in programming. someone told me to use strtok. But I don't know how to do it. Does anyone have any Arduino code to do this?

I tried DFRobot SIM808 library to collect GPS data. it works like charm. But the problem was, my upload code didn't work when i was using the library to collect longitude and latitude in the same code.

This is my web upload code.

#include <SoftwareSerial.h>
#include <String.h>
SoftwareSerial mySerial(10, 11);//(2,3)
void setup()
{
 mySerial.begin(2400); // the GPRS baud rate 9600 
 Serial.begin(2400); // the GPRS baud rate 9600
 delay(1000);
 ShowSerialData();
}
void loop()
{
 Send2Pachube();
 if (mySerial.available())
 Serial.write(mySerial.read());
}
void Send2Pachube()
{
 mySerial.println("AT");//start with attention
 delay(1000);
 mySerial.println("AT+CPIN?");//check for the sim card
 delay(1000);
 mySerial.println("AT+CREG?");//check for registration and access technology of cell
 delay(1000);
 mySerial.println("AT+CGATT?");//check whether the device is attached to GPRS.0Detch,1Attch
 delay(1000);
 mySerial.println("AT+CIPSHUT");//shut packet data protocol context
 delay(1000);
 mySerial.println("AT+CIPSTATUS");// returns the current connection status
 delay(2000);
 mySerial.println("AT+CIPMUX=0"); //create multi-IP connection(0=single connection)
 delay(2000);
 ShowSerialData();
 mySerial.println("AT+CSTT=\"hutch3g\"");//start task and setting the APN,
 delay(1000);
 ShowSerialData();
 mySerial.println("AT+CIICR");//bring up wireless connection
 delay(3000);
 ShowSerialData();
 mySerial.println("AT+CIFSR");//get local IP adress
 delay(2000);
 ShowSerialData();
 mySerial.println("AT+CGPSINF=0");//get GPS
 delay(2000);
 ShowSerialData();
 mySerial.println("AT+CIPSPRT=0");//starts a TCP or UDP connection
 delay(3000);
 ShowSerialData();
 mySerial.println("AT+CIPSTART=\"TCP\",\"api.thingspeak.com\",\"80\"");//start up the connection
 delay(6000);
 ShowSerialData();
 mySerial.println("AT+CIPSEND");//begin send data to remote server
 delay(4000);
 ShowSerialData();
 String str="GET https://api.thingspeak.com/update?api_key=FF19NVWMPZEWX0XK&field1=100";
 mySerial.println(str);//begin send data to remote server
 delay(4000);
 ShowSerialData();
 mySerial.println((char)26);//sending
 delay(5000);//waitting for reply, important! the time is base on the condition of internet 
 mySerial.println();
 ShowSerialData();
 mySerial.println("AT+CIPSHUT");//close the connection
 delay(100);
 ShowSerialData();
} 
void ShowSerialData()
{
 while(mySerial.available()!=0)
 Serial.write(mySerial.read());
}

• 001: Since the library works in getting the data, maybe you should focus on getting that to work with your code.

Answer 1

First rather than just dumping it to the screen store the data in a char array

char dataBuffer[64];
int dataCount=0;
while ( (mySerial.available()!=0) && (dataCount<63) ) {
 dataBuffer[dataCount] = mySerial.read());
 dataCount++;
}
dataBuffer[dataCount] = 0;

then use strtok to split the string on the : and , characters

char *output;
output = strtok(dataBuffer,":");
// output will now point to everything up to the first : so "CGPSINF" for gps
int field = 0;
while (output != null) {
 field++;
 output = strtok(null,",");
// output will now point to each value in turn
// for CGPSINF:0,6.823375,80.001038,36.300000,
// when field == 1 output=="0"
// when field == 2 output=="6.823375" etc...
}