Arduino - Shield Data Logger

// include the SD library:

#include <SD.h>

// set up variables using the SD utility library functions:

Sd2Card card;

SdVolume volume;

SdFile root;

// change this to match your SD shield or module;

// Arduino Ethernet shield: pin 4

// Adafruit SD shields and modules: pin 10

// Sparkfun SD shield: pin 8

const int chipSelect = 10;

const int prueba = 8;

void setup()

{

 // Open serial communications and wait for port to open:

  Serial.begin(9600);

   while (!Serial) {

    ; // wait for serial port to connect. Needed for Leonardo only

  }

  Serial.print("\nInitializing SD card...");

  // On the Ethernet Shield, CS is pin 4. It's set as an output by default.

  // Note that even if it's not used as the CS pin, the hardware SS pin 

  // (10 on most Arduino boards, 53 on the Mega) must be left as an output 

  // or the SD library functions will not work. 

  pinMode(10, OUTPUT);     // change this to 53 on a mega

  // we'll use the initialization code from the utility libraries

  // since we're just testing if the card is working!

  if (!card.init(SPI_HALF_SPEED, chipSelect)) {

    Serial.println("initialization failed. Things to check:");

    Serial.println("* is a card is inserted?");

    Serial.println("* Is your wiring correct?");

    Serial.println("* did you change the chipSelect pin to match your shield or module?");

    return;

  } else {

   Serial.println("Wiring is correct and a card is present.");

  }

  // print the type of card

  Serial.print("\nCard type: ");

  switch(card.type()) {

    case SD_CARD_TYPE_SD1:

      Serial.println("SD1");

      break;

    case SD_CARD_TYPE_SD2:

      Serial.println("SD2");

      break;

    case SD_CARD_TYPE_SDHC:

      Serial.println("SDHC");

      break;

    default:

      Serial.println("Unknown");

  }

}

void loop()

{

  // Abrimos el fichero. Nota: solo se puede abrir un fichero a la vez. Para abrir un segundo fichero hay que cerrar el anterior.

  File dataFile = SD.open("datalog.txt", FILE_WRITE);

  // si el fichero esta disponible escribir en el:

 if (dataFile)   {

    dataFile.println(prueba);

   dataFile.close();

    // escribe tambien en el Serial:

   //Serial.println(prueba);

  }

 // // Si el fichero no se ha abierto, lanzar un mensaje de error:

  else {

    Serial.println("error opening datalog.txt");

 delay (500);

   return ;

  }

}