Reading SD Card Information

The program below is a slightly modified version of the Arduino example SdFatInfo program. The main change is to define the SPI select of the WIZ5500 Ethernet chip and set it high (unselected) so the sketch can talk to the SD card only.

For the Ethernet shield, put your formatted SD card into the SD card slot (top side up, don't force it, gentle). Put your shield on your Arduino-compatible board. Power the boards with a suitable power supply recommended for the Arduino. Connect the microcontroller board to your computer with a suitable USB cable.

For the Feathers, place the formatted micro-SD card into the micro-SD card slot in the Adalogger Feather. Plug the board into a USB port on your computer.

Using the Arduino IDE software and select the correct type of Arduino-compatible board and the serial port for the board in the Tools menu. You may have to push the reset button for the operating system to see the serial port. Load the following sketch, compile, and run.

The information about the SD card should be displayed on the serial monitor in the IDE.

/*
  SD card test for WIZ5500 Compatible Ethernet Boards

 This example shows how use the utility libraries on which the'
 SD library is based in order to get info about your SD card.
 Very useful for testing a card when you're not sure whether its working or not.

 The circuit:
 * SD card attached to SPI bus as follows:
 ** MOSI - pin 11 on Arduino Uno and Adafruit Metro
 ** MISO - pin 12 on Arduino Uno and Adafruit Metro
 ** CLK - pin 13 on Arduino Uno and Adafruit Metro
 ** CS - depends on your SD card shield or module (see below)

 created  28 Mar 2011 by Limor Fried
 modified 9 Apr 2012 by Tom Igoe
 modified 12 Apr 2018 by Mike Barela
 */
// include the SD library:
#include <SPI.h>
#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 #2971 W5500 by Seeed Studio: Pin 4
// Sparkfun SD shield: pin 8
// Arduino Mega: Pin 53
// MKRZero SD: SDCARD_SS_PIN
const int chipSelect = 4;
//
// Chip Select for W5500 Ethernet (must be set as output in initialization)
const int W5500_SS = 10;

void setup() {
  // Open serial communications and wait for port to open:
  Serial.begin(9600);
  while (!Serial) {
    ; // wait for serial port to connect. Needed for native USB port only
  }

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

  // we'll use the initialization code from the utility libraries
  // since we're just testing if the card is working!
  pinMode(W5500_SS, OUTPUT);     // set the Ethernet SS pin as an output (necessary!)
  digitalWrite(W5500_SS, HIGH);  // but turn off the W5500 chip for now  
  if (!card.init(SPI_HALF_SPEED, chipSelect)) {
    Serial.println("initialization failed. Things to check:");
    Serial.println("* is a card 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");
  }

  // Now we will try to open the 'volume'/'partition' - it should be FAT16 or FAT32
  if (!volume.init(card)) {
    Serial.println("Could not find FAT16/FAT32 partition.\nMake sure you've formatted the card");
    return;
  }

  // print the type and size of the first FAT-type volume
  uint32_t volumesize;
  Serial.print("\nVolume type is FAT");
  Serial.println(volume.fatType(), DEC);
  Serial.println();

  volumesize = volume.blocksPerCluster();    // clusters are collections of blocks
  volumesize *= volume.clusterCount();       // we'll have a lot of clusters
  volumesize *= 512;                         // SD card blocks are always 512 bytes
  Serial.print("Volume size (bytes): ");
  Serial.println(volumesize);
  Serial.print("Volume size (Kbytes): ");
  volumesize /= 1024;
  Serial.println(volumesize);
  Serial.print("Volume size (Mbytes): ");
  volumesize /= 1024;
  Serial.println(volumesize);

  Serial.println("\nFiles found on the card (name, date and size in bytes): ");
  root.openRoot(volume);

  // list all files in the card with date and size
  root.ls(LS_R | LS_DATE | LS_SIZE);
}

void loop(void) {
}

The serial monitor output below is for a micro-SD card formatted in Windows 10 for FAT. It is set for 60MB (it doesn't fill the card, it was an old Raspberry Pi Zero system card). It has several text files and a directory with a couple of files in it. Your Arduino Serial Monitor should display something similar.

This guide was first published on Apr 20, 2018. It was last updated on Apr 20, 2018. This page (Reading SD Card Information) was last updated on Aug 20, 2019.