MicroSD Card Sheild Backward Compatibility

Hello Forums,

I am pretty new to Arduino programming, and have worked on several small projects before, but this is the first project I have done involving writing sensor data to an SD card with a MicroSD card shield.

Anyway, the problem I have is that I have an Uno R2, and when searching online for a MicroSD card shield to with which to record data I accidentally bought one with a pin configuration for the Uno R3 (i.e., with the new 4 pins and other slight changes). I also bought stackable pin headers configured for the R3.

Since these do not fit together properly, I tried connecting between the shield and the board:
pin 8 for CS/SS (recommended by manufacturer as opposed to 4)
pin 11 for MOSI
pin 12 for MISO
pin 13 for CLK/SCK
with jumper wires.

However, the microSD card failed to initialize when when used with the manufacturer’s test code (below).

Is there a correct way to wire a MicroSD Card Shield to an Arduino Uno R2, and if not, what would you suggest? Any thanks would be much appreciated, and sorry if this appears to some to be a bit of a newbie question.

// 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;

// The Sparkfun microSD shield uses pin 8 for CS
const int chipSelect = 8;

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

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

  // 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);

  // 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?");
  } 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:
    case SD_CARD_TYPE_SD2:

  // 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");

  // 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);

  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.print("Volume size (Kbytes): ");
  volumesize /= 1024;
  Serial.print("Volume size (Mbytes): ");
  volumesize /= 1024;

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

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

void loop(void) {


How did you wire up the power and ground? Does the SD shield use 5V or 3.3V?


Yes, it uses 3.3V, which is connected to the 3.3V supply on the Arduino, as is the ground.

Never mind! I figured out the problem - I had the MISO and MOSI lines switched. I fixed this and the sheild is now working exactly as expected, but thanks, el_supremo!