microSD-4-LDR

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

#define GND A0
#define VCC A5

const int chipSelect = 10;

void setup() {
  pinMode(GND, OUTPUT);
  pinMode(VCC, OUTPUT);
  digitalWrite(GND, LOW);
  digitalWrite(VCC, HIGH);

  Serial.begin(9600);

  Serial.print("Initializing SD card...");

  // see if the card is present and can be initialized:
  if (!SD.begin(chipSelect)) {
    Serial.println("Card failed, or not present");
    while (1);
  }
  Serial.println("card initialized.");
}


void loop() {
  // make a string for assembling the data to log:
  String dataString = "";

  // read three sensors and append to the string:
  for (int analogPin = 1; analogPin < 5; analogPin++) {
    int sensor = analogRead(analogPin);
    dataString += String(sensor);
    if (analogPin < 4) {
      dataString += ",";
    }
  }

  // open the file. note that only one file can be open at a time,
  // so you have to close this one before opening another.
  File dataFile = SD.open("datalog2.csv", FILE_WRITE);

  // if the file is available, write to it:
  if (dataFile) {
    dataFile.println(dataString);
    dataFile.close();
    // print serial port:
    Serial.println(dataString);

  }else {
    Serial.println("error opening datalog.txt");
  }
}