SdFat Xiao

#include <Arduino.h>
#include <SPI.h>
#include <SdFat.h>

#define SD_CS_PIN 3
#define LEDPIN 4

SdFat SD;
File dataFile;

void setup()
{
  pinMode(LEDPIN, OUTPUT);
  // Open serial communications and wait for port to open:
  Serial.begin(9600);
  digitalWrite(LEDPIN, HIGH);

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

  if (!SD.begin(SD_CS_PIN))
  {
    Serial.println(" failed!");
    return;
  }
  else
  {
    Serial.println(" done!");
  }

  String fileName;

  fileName = "GPSData_";
  fileName += String("02");
  fileName += String("01");
  fileName += String("2024");
  fileName += String("_");
  fileName += String("15");
  fileName += String("10");
  fileName += String("00");
  fileName += String(".kml");

  Serial.print("File name is: ");
  Serial.println(fileName);

  // open the file. note that only one file can be open at a time,
  // so you have to close this one before opening another.
  // (O_READ | O_WRITE | O_CREAT) erases any previous content and then writes.
  // FILE_WRITE is (O_RDWR | O_CREAT | O_AT_END)
  dataFile = SD.open(fileName, FILE_WRITE);

  // if the file opened okay, write to it:
  if (dataFile)
  {
    Serial.print("Writing to file...");

    dataFile.println("<?xml version=\"1.0\" encoding=\"UTF-8\"?>");
    dataFile.println("<kml xmlns=\"http://www.opengis.net/kml/2.2\">");
    dataFile.println("");
    dataFile.println("  <Document>");
    dataFile.println("    <name>Views with Time</name>");
    dataFile.println("    <open>1</open>");
    dataFile.println("    <description>");
    dataFile.println("      In Google Earth 20, enable historical imagery and sunlight,");
    dataFile.println("      then click on each placemark to fly to that point in time.");
    dataFile.println("    </description>");
    dataFile.println("");
    dataFile.println("    <Placemark>");
    dataFile.println("      <name>Sutro Baths in 1946</name>");
    dataFile.println("      <gx:TimeStamp>");
    dataFile.println("        <when>1946-07-29T05:00:00-08:00</when>");
    dataFile.println("      </gx:TimeStamp>");
    dataFile.println("      <longitude>-122.518172</longitude>");
    dataFile.println("      <latitude>37.778036</latitude>");
    dataFile.println("      <altitude>221.0</altitude>");
    dataFile.println("    </Placemark>");
    dataFile.println("");
    dataFile.println("  </Document>");
    dataFile.println("</kml>");

    dataFile.close();
    Serial.println(" done!");
  }
  else
  {
    // if the file didn't open, print an error:
    Serial.println("Error opening file for writing!!");
  }

  // re-open the file for reading:
  Serial.print("\n\nReading from file: ");
  Serial.println(fileName);
  Serial.println("");

  dataFile = SD.open(fileName, FILE_READ);
  if (dataFile)
  {
    // read from the file until there's nothing else in it:
    while (dataFile.available())
    {
      Serial.write(dataFile.read());
    }
    // close the file:
    dataFile.close();
    Serial.println("\n File read!");
  }
  else
  {
    // if the file didn't open, print an error:
    Serial.println("Error opening file for reading!!");
  }
  Serial.end();
}

void loop()
{
  // nothing happens after setup
}