SD card initialization failed on the Feather Wing

Dear Arduino-Team,

As always, I am verry happy about your help. This time, I have tried to follow this project:
and built a LoRaWAN sniffer with following Adafruit components:

Feather M0 & Feather Wing TFT:

As code, I have used exactly the one provided by Joe on the Github page. It gave me an SD card did not initialize error. Then, I have tried the blank CardInfo example of the SD.h library with both chipSelect = 4 and 10 definitions:
I formatted the 8GB SDHC using SD Formatter to FAT32.

Any idea?
Thank you!

  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) {

Reading the documentation often helps.

The SD Card also has a Chip Select line, labeled SD.
On the Atmega32u4, ATmega328P, nRF52840, SAMD21 M0 or SAMD51 M4 Feather, SD is pin #<see yourself>

Reading the documentation often helps.

Pinouts | Adafruit 2.4" TFT FeatherWing | Adafruit Learning System

The SD Card also has a Chip Select line, labeled SD.
On the Atmega32u4, ATmega328P, nRF52840, SAMD21 M0 or SAMD51 M4 Feather, SD is pin #<see yourself>

Thank you for your reply! Actually, I have also tried pin5 and it is definitely the one to use for SAMD21 but the SD card would still not initialize. Then, I’ve formatted the card again using SD card formatter and created a file called hello.txt. Afterwards, the SD card initialized and data was written onto it. However after unplugging and plugging in the boards, the SD card did not initialize anymore.

Doing the same procedure with formatting and creating a file didn’t help.

Any idea for that?