// Read and write data to and from an SD card using Arduino #include <SPI.h> // Include SPI library (needed for the SD card) #include <SD.h> // Include SD library File myFile; void setup() { // Open serial communications and wait for port to open: Serial.begin(9600); while (!Serial) { ; // wait for serial port to connect. Needed for native USB port only } Serial.print("Initializing SD card..."); if (!SD.begin()) { Serial.println("initialization failed!"); while (1); } Serial.println("initialization done."); // open the file. note that only one file can be open at a time, // so you have to close this one before opening another. myFile = SD.open("test.txt", FILE_WRITE); // if the file opened okay, write to it: if (myFile) { Serial.print("Writing to test.txt..."); myFile.println("testing 1, 2, 3."); // close the file: myFile.close(); Serial.println("done."); } else { // if the file didn't open, print an error: Serial.println("error opening test.txt"); } // re-open the file for reading: myFile = SD.open("test.txt"); if (myFile) { Serial.println("test.txt:"); // read from the file until there's nothing else in it: while (myFile.available()) { Serial.write(myFile.read()); } // close the file: myFile.close(); } else { // if the file didn't open, print an error: Serial.println("error opening test.txt"); } } void loop() { }