Using the SD library to retrieve information over a serial port

/*

  SD card file dump

  This example shows how to read a file from the SD card using the

  SD library and send it over the serial port.

  Pin numbers reflect the default SPI pins for Uno and Nano models.

  The circuit:

   SD card attached to SPI bus as follows:

 ** SDO - pin 11

 ** SDI - pin 12

 ** CLK - pin 13

 ** CS - depends on your SD card shield or module.

        Pin 10 used here for consistency with other Arduino examples

   (for MKRZero SD: SDCARD_SS_PIN)

  created  22 December 2010

  by Limor Fried

  modified 9 Apr 2012

  by Tom Igoe

  This example code is in the public domain.

*/
#include <SD.h>

const int chipSelect = 10;

void setup() {

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

  Serial.begin(9600);

  // wait for Serial Monitor to connect. Needed for native USB port boards only:

  while (!Serial);

  Serial.print("Initializing SD card...");

  if (!SD.begin(chipSelect)) {

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

    Serial.println("1. is a card inserted?");

    Serial.println("2. is your wiring correct?");

    Serial.println("3. did you change the chipSelect pin to match your shield or module?");

    Serial.println("Note: press reset or reopen this serial monitor after fixing your issue!");

    while (true);

  }

  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.

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

  // if the file is available, write to it:

  if (dataFile) {

    while (dataFile.available()) {

      Serial.write(dataFile.read());

    }

    dataFile.close();

  }

  // if the file isn't open, pop up an error:

  else {

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

  }
}

void loop() {
}