Thanks for the advice, but i really confuse how to start. i use SD.h library to write the data to SD card. below is my code
#include <TinyGPS.h>
#include <SD.h>
#include <stdlib.h>
#include <SPI.h>
#include <Ethernet.h>
TinyGPS gps;
static char dtostrfbuffer[20];
int CS = 4;
int LED = 13;
//Define String
String SD_date_time = "invalid";
String SD_lat = "invalid";
String SD_lon = "invalid";
String SD_speed = "invalid";
String SD_heading = "invalid";
String dataString ="";
static void gpsdump(TinyGPS &gps);
static bool feedgps();
static void print_float(float val, float invalid, int len, int prec, int SD_val);
static void print_int(unsigned long val, unsigned long invalid, int len);
static void print_date(TinyGPS &gps);
static void print_str(const char *str, int len);
void setup()
{
pinMode(CS, OUTPUT); //Chip Select untuk SD Card
pinMode(LED, OUTPUT); //LED Indicator
pinMode(53, OUTPUT); //chip select pin
//Serial interfaces
Serial.begin(9600);
Serial3.begin(4800);
// ethernet
while (!Serial) {
; // wait for serial port to connect. Needed for Leonardo only
}
//Connect to the SD Card
if(!SD.begin(CS))
{
Serial.println("Card Failure");
return;
}
}
void loop()
{
bool newdata = false;
unsigned long start = millis();
// get data
while (millis() - start < 2000)
{
if (feedgps())
newdata = true;
}
gpsdump(gps);
//write to sd card
dataString = SD_date_time + "," + SD_lat + "," + SD_lon + "," + SD_speed + "," + SD_heading;
if(SD_date_time != "invalid")
digitalWrite(LED, HIGH);
else
digitalWrite(LED, LOW);
//open file log.txt
File dataFile = SD.open("LOG.txt", FILE_WRITE);
if (dataFile)
{
dataFile.print("CRM001");
dataFile.print(", ");
dataFile.println(dataString);
Serial.println(dataString);
dataFile.close();
}
else
{
Serial.println("\nCouldn't open the log file!");
}
}
static void gpsdump(TinyGPS &gps)
{
float flat, flon;
unsigned long age, date, time, chars = 0;
unsigned short sentences = 0, failed = 0;
print_int(gps.satellites(), TinyGPS::GPS_INVALID_SATELLITES, 5);
print_int(gps.hdop(), TinyGPS::GPS_INVALID_HDOP, 5);
gps.f_get_position(&flat, &flon, &age);
print_float(flat, TinyGPS::GPS_INVALID_F_ANGLE, 9, 5, 1); //LATITUDE
print_float(flon, TinyGPS::GPS_INVALID_F_ANGLE, 10, 5, 2); //LONGITUDE
print_int(age, TinyGPS::GPS_INVALID_AGE, 5);
print_date(gps); //DATE AND TIME
print_float(gps.f_altitude(), TinyGPS::GPS_INVALID_F_ALTITUDE, 8, 2, 0);
print_float(gps.f_course(), TinyGPS::GPS_INVALID_F_ANGLE, 7, 2, 4);
print_float(gps.f_speed_kmph(), TinyGPS::GPS_INVALID_F_SPEED, 6, 2, 3);
print_str(gps.f_course() == TinyGPS::GPS_INVALID_F_ANGLE ? "*** " : TinyGPS::cardinal(gps.f_course()), 6);
}
static void print_int(unsigned long val, unsigned long invalid, int len)
{
char sz[32];
if (val == invalid)
strcpy(sz, "*******");
else
sprintf(sz, "%ld", val);
sz[len] = 0;
for (int i=strlen(sz); i<len; ++i)
sz[i] = ' ';
if (len > 0)
sz[len-1] = ' ';
//Serial.print(sz);
feedgps();
}
static void print_float(float val, float invalid, int len, int prec, int SD_val)
{
char sz[32];
if (val == invalid)
{
strcpy(sz, "*******");
sz[len] = 0;
if (len > 0)
sz[len-1] = ' ';
for (int i=7; i<len; ++i)
sz[i] = ' ';
//Serial.print(sz);
if(SD_val == 1) SD_lat = sz;
else if(SD_val == 2) SD_lon = sz;
else if(SD_val== 3) SD_speed = sz;
else if(SD_val== 4) SD_heading = sz;
}
else
{
//Serial.print(val, prec);
if (SD_val == 1) SD_lat = dtostrf(val,10,5,dtostrfbuffer);
else if (SD_val == 2) SD_lon = dtostrf(val,10,5,dtostrfbuffer);
else if (SD_val == 3) SD_speed = dtostrf(val,10,2,dtostrfbuffer);
else if (SD_val == 4) SD_heading = dtostrf(val,10,2,dtostrfbuffer);
int vi = abs((int)val);
int flen = prec + (val < 0.0 ? 2 : 1);
flen += vi >= 1000 ? 4 : vi >= 100 ? 3 : vi >= 10 ? 2 : 1;
for (int i=flen; i<len; ++i)
Serial.print(" ");
}
feedgps();
}
static void print_date(TinyGPS &gps)
{
int year;
byte month, day, hour, minute, second, hundredths;
unsigned long age;
gps.crack_datetime(&year, &month, &day, &hour, &minute, &second, &hundredths, &age);
if (age == TinyGPS::GPS_INVALID_AGE)
{
//Serial.print("******* ******* ");
SD_date_time = "invalid";
}
else
{
char sz[32];
sprintf(sz, "%02d-%02d-%02d %02d:%02d:%02d ",
year, month, day, hour, minute, second);
//Serial.print(sz);
SD_date_time = sz;
}
print_int(age, TinyGPS::GPS_INVALID_AGE, 5);
feedgps();
}
static void print_str(const char *str, int len)
{
int slen = strlen(str);
for (int i=0; i<len; ++i)
//Serial.print(i<slen ? str[i] : ' ');
feedgps();
}
static bool feedgps()
{
while (Serial3.available())
{
if (gps.encode(Serial3.read()))
return true;
}
return false;
}
the code above is taken from a tutorial somewhere on the net, now the first thing i want to do is how can i read the LOG.txt file and print it to serial. I've try readwrite sample and it works...but when i combine with the code above it become not working. may be it because i write and read at the same time. How can i log the data every 10 second and use the time between it to read the LOG.txt