SD Card Module Fat formatting issue

I’m trying to setup this SD Card module (SD Card Module | Core Electronics Australia) with an arduino UNO and SanDisk SDHC 32GB card.

I connect the SD Card module as shown in the diagram with the chip select connected to the default pin 4 (I have also tried setting the chip select to pin 10). I’m using the 3.3V supply from the UNO to power the SD Card module.

I’m using version 1.2.4 of the SD library and running the CardInfo example on the Arduino IDE and I get the following error message.

Initializing SD card...Wiring is correct and a card is present.

Card type:         SDHC
Could not find FAT16/FAT32 partition.
Make sure you've formatted the card

I’ve formatted the card and after reading some posts online, ensured that the card is FAT32 with an MBR partition table. I’ve tried formatting using different applications including the primary suggested one by SD Association (SD Memory Card Formatter | SD Association). This shows the SD card properties after formatting with the SD Association program.

I’ve also tried to create a smaller 4GB partition on the SD card but it returns the same error as above.

A few other posts have suggested some other ideas which I have tried without success:

  • Setting the SPI to quarter speed instead of half speed in the CardInfo sketch (same error)
  • Instead using the sdFat lib, this returns a similar error indicating the formatting is incorrect

Hi Scott,

Sorry to hear that SD adapter is giving you trouble. I found the code in the library that generates that warning:

Have you checked the cluster size? The guide for that example suggests this guide on calculating the right values to use during formatting, but I’m not sure how that relates to the SD library. Try 512 bytes and let us know how that goes.

Thanks James, I was using the default cluster size which for my 32GB SD card was 16KB.

I changed to 512 bytes (see image below) but I still get the exact same error. I had to use GNU parted to create the partition given the cluster size, the SD card association didn’t allow me to specify the cluster size.

I did some further digging into the error and found that it comes from the SPI communication. I’ve put some pictures of the execution sequence below. The return from the cardCommand function is what causes the error.


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Another update:

I’ve found a temporary solution. In the SD library as shown below I added a small delay which must be greater than or equal to 6ms and then I get the expected output of the CardInfo example.


I don’t understand why though, it seems that the SPI is busy and waiting for 6ms is enough to wait this out. But this should be taken care of the waitNotBusy function.

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Hi Scott,

Thanks for sharing your fixes! Having one set up on your end does mean you can get to the solution faster than we can.

We’ll keep this in mind if anyone asks about this in future.

I am facing same issue. I have two Ardunio one UNO and another At mega 2560 but facing same problem “Could not find FAT16/FAT32 partition” i am using an GB micro sd card i am testing may code with CardInfo example.

If any of u have any solution feel free to help

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Hi @MOHAMMADSHOAIB267093 - welcome to the forums :slight_smile:
Did you try the solution that worked for Scott?

It may be that your particular card requires a bit more of a delay before being ready for new commands

No that dosent work for me

this the code i am using

  SD card test

  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/Duemilanove/Diecimila
 ** MISO - pin 12 on Arduino Uno/Duemilanove/Diecimila
 ** CLK - pin 13 on Arduino Uno/Duemilanove/Diecimila
 ** CS - depends on your SD card shield or module.
 		Pin 4 used here for consistency with other Arduino examples

  created  28 Mar 2011
  by Limor Fried
  modified 9 Apr 2012
  by Tom Igoe
// 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 SD shields and modules: pin 10
// Sparkfun SD shield: pin 8
const int chipSelect = 4;

void setup() {
  // Open serial communications and wait for port to open:
  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!
  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?");
    while (1);
  } else {
    Serial.println("Wiring is correct and a card is present.");

  // print the type of card
  Serial.print("Card 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");
    while (1);

  Serial.print("Clusters:          ");
  Serial.print("Blocks x Cluster:  ");

  Serial.print("Total Blocks:      ");
  Serial.println(volume.blocksPerCluster() * volume.clusterCount());

  // print the type and size of the first FAT-type volume
  uint32_t volumesize;
  Serial.print("Volume 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 /= 2;                           // SD card blocks are always 512 bytes (2 blocks are 1KB)
  Serial.print("Volume size (Kb):  ");
  Serial.print("Volume size (Mb):  ");
  volumesize /= 1024;
  Serial.print("Volume size (Gb):  ");
  Serial.println((float)volumesize / 1024.0);

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

  // list all files in the card with date and size | LS_DATE | LS_SIZE);

void loop(void) {

As a sanity check - is the card already formatted for FAT32?

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