SD card not getting Data

Hello all,

For some reason my MKR Zero is not writing to the SD card. It will create a file but when I go look at said file on a computer there is zero bytes written to it, and no text…

So I’m using a MKR Zero with 16 GB SanDisk microSd formatted Fat32

Here is the code I’ve been testing
I’ve tried a couple different chip select values and none seem to work (4, SS1, SDCARD_SS_PIN) with no success. I’m a bit stumped… hopefully one of you guys can point me in right direction

#include <SPI.h>
#include <SD.h>
#include <Wire.h>

const int chipSelect = SDCARD_SS_PIN;
File logfile;

void setup() {
  // put your setup code here, to run once:

if (!SD.begin(chipSelect)) {
    Serial.println("Card failed, or not present");
    // don't do anything more:
    //return;  //uncomment if want setup to stop if no SD available

  if (SD.begin(chipSelect)) {
    Serial.println("card initialized.");
  // create a new file
  char filename[] = "LOGGER00.TXT";
  for (uint8_t i = 0; i < 100; i++) {
    filename[6] = i / 10 + '0';
    filename[7] = i % 10 + '0';
    if (! SD.exists(filename)) {
      // only open a new file if it doesn't exist
      logfile =, FILE_WRITE);
 if (! logfile) {
    Serial.println("couldnt create file");
  else {
    Serial.print("Logging to: ");

    logfile.println("This is a test file");
    // if ECHO_TO_SERIAL
    Serial.println("This is a test file");
  if (!logfile.println() ) {
    Serial.println("error with write header");

Serial.println("System ready...");


void loop() {
  // put your main code here, to run repeatedly:

digitalWrite(LED_BUILTIN, HIGH);

logfile.print("Hello World");
Serial.println("Hello World");

  Serial.println("SD printing failed");
digitalWrite(LED_BUILTIN, LOW);


As far as debugging goes heres what I’ve got in the serial monitor:
with SD card in the Arduino, continuous prints of Hello World,
with SD card pulled out of Arduino when on: “Hello World” followed by “SD printing failed”

Nevermind all, realized I have to close/flush to get it to save....