I have two successfully working individual programs, 1.GPS coordinate extract program. 2.EEPROM saving and reading program. now all I want to do is combine them both, whenever GPS location is updated ,I want to save that latitude data to EEPROM memory repalcing the previously saved data, but I guess my program is unable to save it,its just showing blank spaces when reading EEPROM,please help me guys..here is my code.

#include <SoftwareSerial.h> 
#include <TinyGPS++.h>
#define RXPin 8
#define TXPin 9
#define GPSBaud 9600
#define ConsoleBaud 9600

// The serial connection to the GPS device
SoftwareSerial ss(RXPin, TXPin);

// The TinyGPS++ object
TinyGPSPlus gps;
#include <EEPROM.h>
int address = 0; 
int read_value = 0; 
char data;
void setup()
  Serial.println("Previous value stored :");
  for(address = 0; address < 25; address ++)        // read the entire EEPROM memory
    read_value = EEPROM.read(address);


void loop()

  while (ss.available() > 0)

  if (gps.location.isUpdated() || gps.altitude.isUpdated())
    Serial.print("Location: "); 
    Serial.print(gps.location.lat(), 6);
    Serial.print(gps.location.lng(), 6);

    data=(gps.location.lat(), 6);

    for(address = 0; address < 25;  )
      EEPROM.write(address, data); 
      address ++;
  • data=(gps.location.lat(), 6); just always stores 6 in data, this is what will be sotored on all 25 first locations of EEPROM. It looks you don't understand what you're doing with this code. I'd recommend taking a look at some basic C programming tutorial.
    – jfpoilpret
    Oct 5, 2014 at 12:27

2 Answers 2


Consider TinyGPS++ over TinyGPS only if you are running on Due or processor which can take advantage of the higher precision of 64-bit “double” floating-point.

char data; should be double data;. You're wasting resources otherwise.

data=(gps.location.lat(), 6); isn't how you do it. You only need to specify precision when writing to Serial, like Serial.print(gps.location.lat(), 6);. Make it data = gps.location.lat();.

address ++; should be address = address <=512-sizeof(address) ? (address + sizeof(data)): 0 ;

address <=512-sizeof(address) ensures that the last value written to the EEPROM is written in it's entirety.

Alternatively, I would recommend this to save you data structure directly to EEPROM, and what @jfpoilpret mentions.


You might try using sprintf. First define a buffer:

char data[25];

Then use sprintf to print to the buffer:

sprintf(data, "Location: %.3f,%.3f\n", gps.location.lat(), gps.location.lon());

%.3f prints a float with 3 decimal places. Check out the printf reference for details.

Then write the buffer to EEPROM:

for(address = 0; address < 25; address++ )
  EEPROM.write(address, data);
  • Careful with lat() and lon(): those return a double not an int! Hence sprintf("...%d...") will not work unless you explicitly cast lat() and lon() return to int.
    – jfpoilpret
    Oct 5, 2014 at 18:03
  • well spotted @jfpoilpret :P Oct 6, 2014 at 0:12

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