#include <SoftwareSerial.h>
#include <TinyGPS++.h>
#include <SD.h>

#define GPS_TX 2 // TX pin of GPS module connected to Arduino's RX pin
#define GPS_RX 3 // RX pin of GPS module connected to Arduino's TX pin
#define SD_CS 10 // Chip select pin of SD module
#define SD_CD 9 // Card detect pin of SD module

SoftwareSerial gpsSerial(GPS_TX, GPS_RX);
TinyGPSPlus gps;
File gpsFile;

void setup() {
  Serial.begin(9600);
  gpsSerial.begin(9600);

  pinMode(SD_CD, INPUT_PULLUP); // Set SD card detect pin as input with internal pull-up resistor

  if (!SD.begin(SD_CS)) {
    Serial.println("Failed to initialize SD card!");
    return;
  }

  gpsFile = SD.open("gps_data.txt", FILE_WRITE);
  if (!gpsFile) {
    Serial.println("Failed to open file!");
    return;
  }

  gpsFile.println("Latitude,Longitude");
}

void loop() {
  while (gpsSerial.available() > 0) {
    if (gps.encode(gpsSerial.read())) {
      if (gps.location.isValid()) {
        Serial.print("Latitude= ");
        Serial.print(gps.location.lat(), 6);
        Serial.print(" Longitude= ");
        Serial.println(gps.location.lng(), 6);
        
        gpsFile.print(gps.location.lat(), 6);
        gpsFile.print(",");
        gpsFile.println(gps.location.lng(), 6);
      } else {
        Serial.println("Location not available");
      }
    }
  }

  // Check if SD card is inserted
  if (digitalRead(SD_CD) == LOW) {
    Serial.println("SD card detected!");
  } else {
    Serial.println("SD card not detected!");
  }
  
  delay(1000); // Delay for stability
}