➯ https://www.arduino.cc/en/reference/SD

• https://github.com/greiman/SdFat

#include <SPI.h>
#include <SD.h>
Sd2Card card;
SdVolume volume;
SdFile root;
const int chipSelect = 10;
void setup() {
 Serial.begin(9600);
 while (!Serial) {
 } 
 
 Serial.print("\nInitializing SD card...");
 if (!card.init(SPI_HALF_SPEED, chipSelect)) {
   Serial.println("initialization failed");
   return;
 } else {
   Serial.println("Wiring is correct and a card is present.");
 }
 Serial.print("\nCard type: ");
 switch (card.type()) {
   case SD_CARD_TYPE_SD1:
     Serial.println("SD1");
     break;
   case SD_CARD_TYPE_SD2:
     Serial.println("SD2");
     break;
   case SD_CARD_TYPE_SDHC:
     Serial.println("SDHC");
     break;
   default:
     Serial.println("Unknown");
 }
 if (!volume.init(card)) {
   Serial.println("Could not find FAT16/FAT32 partition.\nMake sure you've formatted the card");
   return;
 }
 uint32_t volumesize;
 Serial.print("\nVolume type is FAT");
 Serial.println(volume.fatType(), DEC);
 Serial.println();
 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.println(volumesize);
 Serial.print("Volume size (Kbytes): ");
 volumesize /= 1024;
 Serial.println(volumesize);
 Serial.print("Volume size (Mbytes): ");
 volumesize /= 1024;
 Serial.println(volumesize);
 Serial.println("\nFiles found on the card (name, date and size in bytes): ");
 root.openRoot(volume);
 root.ls(LS_R | LS_DATE | LS_SIZE);
}
void loop(void) {}

#include <SPI.h>
#include <SD.h>
File myFile;
String buffer;    
void setup() {
 Serial.begin(9600);
 while (!Serial) {
 }
 Serial.print("Initializing SD card...");
 if (!SD.begin(4)) {
   Serial.println("initialization failed!");
   return;
 }
 Serial.println("initialization done.");
 myFile = SD.open("test.txt", FILE_WRITE);
 if (myFile) {
   Serial.print("Writing to test.txt...");
   myFile.println("testing 1, 2, 3.");
   myFile.close();
   Serial.println("done.");
 } else {
   Serial.println("error opening test.txt");
 }
//Read file byte by byte
myFile = SD.open("test.txt");
 if (myFile) {
   Serial.println("Read test.txt byte by byte:");
   while (myFile.available()) {
     Serial.write(myFile.read());
   }
   myFile.close();
 } else {
   Serial.println("error opening test.txt");
 }
  //Read file line by line 
  myFile = SD.open("test.txt");
  if (myFile) {
   Serial.println("Read test.txt line by line:");
 
   while (myFile.available()) {
       buffer = myFile.readStringUntil('\n');
       Serial.println(buffer);
       }
   myFile.close();  
  } else {    
   Serial.println("error opening test.txt");  
  }
}
void loop() { }

• https://github.com/fivitti/Arduino-CSV-File