Logging Accelerometer and GPS Data

For my parts, I am using the Adafruit Ultimate GPS+Logging Shield and the SparkFun ADXL345 Accelerometer. The accelerometer is connected via I2C. My current code is able to print all of my data to the serial monitor, but I don't know how I would store that data to the SD card on the Ultimate GPS+Logging Shield. Thank you for your time!

My Code:

#include <Adafruit_GPS.h>
#include <SoftwareSerial.h>
#include <SparkFun_ADXL345.h>
#include <SPI.h>
#include <SD.h>

SoftwareSerial mySerial(8, 7);
ADXL345 adxl = ADXL345(); 


Adafruit_GPS GPS(&mySerial);


// Set GPSECHO to 'false' to turn off echoing the GPS data to the Serial console
// Set to 'true' if you want to debug and listen to the raw GPS sentences. 
#define GPSECHO  false

// this keeps track of whether we're using the interrupt
// off by default!
boolean usingInterrupt = false;
void useInterrupt(boolean); // Func prototype keeps Arduino 0023 happy

void setup()  
{
  adxl.powerOn();                     // Power on the ADXL345

  adxl.setRangeSetting(16);           // Give the range settings
                                      // Accepted values are 2g, 4g, 8g or 16g
                                      // Higher Values = Wider Measurement Range
                                      // Lower Values = Greater Sensitivity
  // connect at 115200 so we can read the GPS fast enough and echo without dropping chars
  // also spit it out
  Serial.begin(115200);
  Serial.println("Adafruit GPS library basic test!");

  // 9600 NMEA is the default baud rate for Adafruit MTK GPS's- some use 4800
  GPS.begin(9600);
  
  // uncomment this line to turn on RMC (recommended minimum) and GGA (fix data) including altitude
  GPS.sendCommand(PMTK_SET_NMEA_OUTPUT_RMCGGA);
  // uncomment this line to turn on only the "minimum recommended" data
  //GPS.sendCommand(PMTK_SET_NMEA_OUTPUT_RMCONLY);
  // For parsing data, we don't suggest using anything but either RMC only or RMC+GGA since
  // the parser doesn't care about other sentences at this time
  
  // Set the update rate
  GPS.sendCommand(PMTK_SET_NMEA_UPDATE_1HZ);   // 1 Hz update rate
  // For the parsing code to work nicely and have time to sort thru the data, and
  // print it out we don't suggest using anything higher than 1 Hz

  // Request updates on antenna status, comment out to keep quiet
  GPS.sendCommand(PGCMD_ANTENNA);

  // the nice thing about this code is you can have a timer0 interrupt go off
  // every 1 millisecond, and read data from the GPS for you. that makes the
  // loop code a heck of a lot easier!
  useInterrupt(true);

  delay(1000);
  // Ask for firmware version
  mySerial.println(PMTK_Q_RELEASE);
}


// Interrupt is called once a millisecond, looks for any new GPS data, and stores it
SIGNAL(TIMER0_COMPA_vect) {
  char c = GPS.read();
  // if you want to debug, this is a good time to do it!
#ifdef UDR0
  if (GPSECHO)
    if (c) UDR0 = c;  
    // writing direct to UDR0 is much much faster than Serial.print 
    // but only one character can be written at a time. 
#endif
}

void useInterrupt(boolean v) {
  if (v) {
    // Timer0 is already used for millis() - we'll just interrupt somewhere
    // in the middle and call the "Compare A" function above
    OCR0A = 0xAF;
    TIMSK0 |= _BV(OCIE0A);
    usingInterrupt = true;
  } else {
    // do not call the interrupt function COMPA anymore
    TIMSK0 &= ~_BV(OCIE0A);
    usingInterrupt = false;
  }
}

uint32_t timer = millis();
void loop()                     // run over and over again
{
  int x,y,z;   
  adxl.readAccel(&x, &y, &z);         // Read the accelerometer values and store them in variables declared above x,y,z

  // Output Results to Serial
  /* UNCOMMENT TO VIEW X Y Z ACCELEROMETER VALUES */  
  Serial.print(x);
  Serial.print(", ");
  Serial.print(y);
  Serial.print(", ");
  Serial.println(z); 
  
  // in case you are not using the interrupt above, you'll
  // need to 'hand query' the GPS, not suggested :(
  if (! usingInterrupt) {
    // read data from the GPS in the 'main loop'
    char c = GPS.read();
    // if you want to debug, this is a good time to do it!
    if (GPSECHO)
      if (c) Serial.print(c);
  }
  
  // if a sentence is received, we can check the checksum, parse it...
  if (GPS.newNMEAreceived()) {
    // a tricky thing here is if we print the NMEA sentence, or data
    // we end up not listening and catching other sentences! 
    // so be very wary if using OUTPUT_ALLDATA and trytng to print out data
    //Serial.println(GPS.lastNMEA());   // this also sets the newNMEAreceived() flag to false
  
    if (!GPS.parse(GPS.lastNMEA()))   // this also sets the newNMEAreceived() flag to false
      return;  // we can fail to parse a sentence in which case we should just wait for another
  }

  // if millis() or timer wraps around, we'll just reset it
  if (timer > millis())  timer = millis();

  // approximately every 2 seconds or so, print out the current stats
  if (millis() - timer > 1000) { 
    timer = millis(); // reset the timer
    
    Serial.print("\nTime: ");
    Serial.print(GPS.hour, DEC); Serial.print(':');
    Serial.print(GPS.minute, DEC); Serial.print(':');
    Serial.print(GPS.seconds, DEC); Serial.print('.');
    Serial.println(GPS.milliseconds);
    Serial.print("Date: ");
    Serial.print(GPS.day, DEC); Serial.print('/');
    Serial.print(GPS.month, DEC); Serial.print("/20");
    Serial.println(GPS.year, DEC);
    Serial.print("Fix: "); Serial.print((int)GPS.fix);
    Serial.print(" quality: "); Serial.println((int)GPS.fixquality); 
    if (GPS.fix) {
      Serial.print("Location: ");
      Serial.print(GPS.latitude, 4); Serial.print(GPS.lat);
      Serial.print(", "); 
      Serial.print(GPS.longitude, 4); Serial.println(GPS.lon);
      Serial.print("Location (in degrees, works with Google Maps): ");
      Serial.print(GPS.latitudeDegrees, 4);
      Serial.print(", "); 
      Serial.println(GPS.longitudeDegrees, 4);
      
      Serial.print("Speed (knots): "); Serial.println(GPS.speed);
      Serial.print("Angle: "); Serial.println(GPS.angle);
      Serial.print("Altitude: "); Serial.println(GPS.altitude);
      Serial.print("Satellites: "); Serial.println((int)GPS.satellites);
    }
  }
}

As I am trying to stitch together the two codes, I get this in the serial moniter: "Initializing SD card...initialization done.
error opening test.txt"
It then loops and prints "Initializing SD card" until I stop it.

Code:

#include <Adafruit_GPS.h>
#include <SoftwareSerial.h>
#include <SparkFun_ADXL345.h>
#include <SPI.h>
#include <SD.h>

SoftwareSerial mySerial(8, 7);
ADXL345 adxl = ADXL345(); 

File myFile;

Adafruit_GPS GPS(&mySerial);


// Set GPSECHO to 'false' to turn off echoing the GPS data to the Serial console
// Set to 'true' if you want to debug and listen to the raw GPS sentences. 
#define GPSECHO  false

// this keeps track of whether we're using the interrupt
// off by default!
boolean usingInterrupt = false;
void useInterrupt(boolean); // Func prototype keeps Arduino 0023 happy

void setup()  
{
  Serial.begin(115200);
  adxl.powerOn();                     // Power on the ADXL345

  adxl.setRangeSetting(16);           // Give the range settings
                                      // Accepted values are 2g, 4g, 8g or 16g
                                      // Higher Values = Wider Measurement Range
                                      // Lower Values = Greater Sensitivity
  
  Serial.print("Initializing SD card...");

  if (!SD.begin(10)) {
    Serial.println("initialization failed!");
    while (1);
  }
  Serial.println("initialization done.");

  // open the file. note that only one file can be open at a time,
  // so you have to close this one before opening another.
  myFile = SD.open("test.txt", FILE_WRITE);

  // if the file opened okay, write to it:
  if (myFile) {
    Serial.print("Writing to test.txt...");
    myFile.println("testing 1, 2, 3.");
    // close the file:
    myFile.close();
    Serial.println("done.");
  } else {
    // if the file didn't open, print an error:
    Serial.println("error opening test.txt");
  }

  // connect at 115200 so we can read the GPS fast enough and echo without dropping chars
  // also spit it out


  // 9600 NMEA is the default baud rate for Adafruit MTK GPS's- some use 4800
  GPS.begin(9600);
  
  // uncomment this line to turn on RMC (recommended minimum) and GGA (fix data) including altitude
  GPS.sendCommand(PMTK_SET_NMEA_OUTPUT_RMCGGA);
  // uncomment this line to turn on only the "minimum recommended" data
  //GPS.sendCommand(PMTK_SET_NMEA_OUTPUT_RMCONLY);
  // For parsing data, we don't suggest using anything but either RMC only or RMC+GGA since
  // the parser doesn't care about other sentences at this time
  
  // Set the update rate
  GPS.sendCommand(PMTK_SET_NMEA_UPDATE_1HZ);   // 1 Hz update rate
  // For the parsing code to work nicely and have time to sort thru the data, and
  // print it out we don't suggest using anything higher than 1 Hz

  // Request updates on antenna status, comment out to keep quiet
  GPS.sendCommand(PGCMD_ANTENNA);

  // the nice thing about this code is you can have a timer0 interrupt go off
  // every 1 millisecond, and read data from the GPS for you. that makes the
  // loop code a heck of a lot easier!
  useInterrupt(true);

  delay(1000);
  // Ask for firmware version
  mySerial.println(PMTK_Q_RELEASE);
}


// Interrupt is called once a millisecond, looks for any new GPS data, and stores it
SIGNAL(TIMER0_COMPA_vect) {
  char c = GPS.read();
  // if you want to debug, this is a good time to do it!
#ifdef UDR0
  if (GPSECHO)
    if (c) UDR0 = c;  
    // writing direct to UDR0 is much much faster than Serial.print 
    // but only one character can be written at a time. 
#endif
}

void useInterrupt(boolean v) {
  if (v) {
    // Timer0 is already used for millis() - we'll just interrupt somewhere
    // in the middle and call the "Compare A" function above
    OCR0A = 0xAF;
    TIMSK0 |= _BV(OCIE0A);
    usingInterrupt = true;
  } else {
    // do not call the interrupt function COMPA anymore
    TIMSK0 &= ~_BV(OCIE0A);
    usingInterrupt = false;
  }
}

uint32_t timer = millis();
void loop()                     // run over and over again
{
  int x,y,z;   
  adxl.readAccel(&x, &y, &z);         // Read the accelerometer values and store them in variables declared above x,y,z

  // Output Results to Serial
  /* UNCOMMENT TO VIEW X Y Z ACCELEROMETER VALUES */  
  Serial.print(x);
  Serial.print(", ");
  Serial.print(y);
  Serial.print(", ");
  Serial.println(z); 
  
  // in case you are not using the interrupt above, you'll
  // need to 'hand query' the GPS, not suggested :(
  if (! usingInterrupt) {
    // read data from the GPS in the 'main loop'
    char c = GPS.read();
    // if you want to debug, this is a good time to do it!
    if (GPSECHO)
      if (c) Serial.print(c);
  }
  
  // if a sentence is received, we can check the checksum, parse it...
  if (GPS.newNMEAreceived()) {
    // a tricky thing here is if we print the NMEA sentence, or data
    // we end up not listening and catching other sentences! 
    // so be very wary if using OUTPUT_ALLDATA and trytng to print out data
    //Serial.println(GPS.lastNMEA());   // this also sets the newNMEAreceived() flag to false
  
    if (!GPS.parse(GPS.lastNMEA()))   // this also sets the newNMEAreceived() flag to false
      return;  // we can fail to parse a sentence in which case we should just wait for another
  }

  // if millis() or timer wraps around, we'll just reset it
  if (timer > millis())  timer = millis();

  // approximately every 2 seconds or so, print out the current stats
  if (millis() - timer > 1000) { 
    timer = millis(); // reset the timer
    
    Serial.print("\nTime: ");
    Serial.print(GPS.hour, DEC); Serial.print(':');
    Serial.print(GPS.minute, DEC); Serial.print(':');
    Serial.print(GPS.seconds, DEC); Serial.print('.');
    Serial.println(GPS.milliseconds);
    Serial.print("Date: ");
    Serial.print(GPS.day, DEC); Serial.print('/');
    Serial.print(GPS.month, DEC); Serial.print("/20");
    Serial.println(GPS.year, DEC);
    Serial.print("Fix: "); Serial.print((int)GPS.fix);
    Serial.print(" quality: "); Serial.println((int)GPS.fixquality); 
    if (GPS.fix) {
      Serial.print("Location: ");
      Serial.print(GPS.latitude, 4); Serial.print(GPS.lat);
      Serial.print(", "); 
      Serial.print(GPS.longitude, 4); Serial.println(GPS.lon);
      Serial.print("Location (in degrees, works with Google Maps): ");
      Serial.print(GPS.latitudeDegrees, 4);
      Serial.print(", "); 
      Serial.println(GPS.longitudeDegrees, 4);
      
      Serial.print("Speed (knots): "); Serial.println(GPS.speed);
      Serial.print("Angle: "); Serial.println(GPS.angle);
      Serial.print("Altitude: "); Serial.println(GPS.altitude);
      Serial.print("Satellites: "); Serial.println((int)GPS.satellites);
    }
  }
}

I am trying to stitch together the two codes

This is a common, but poor way to proceed.

You write code, once you fully understand how the individual, properly functioning examples work.

In this particular case, you need to consult the documentation for sd.open() to understand why the open command failed.

Duplicate thread to here: Need help logging Sparkfun ADXL345 Accelerometer data to SD card. - #8 by DylanZapzalka - Programming Questions - Arduino Forum

Same OP, Same topic. Not sure why it would produce a different answer.