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

#define ONE_WIRE_BUS 7 // Data wire is plugged into pin 7 of the arduino

// Setup a OneWire instance to communicate with any OneWire devices
OneWire oneWire(ONE_WIRE_BUS);

// Pass OneWire reference to Dallas Temperature
DallasTemperature sensors(&oneWire);

const int chipSelect = 10;
long id = 0; 

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
  }

  sensors.begin(); // Start up the library

  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");
    // don't do anything more:
    while (1);
  }
  Serial.println("card initialized.");
}

void loop() {
  // call sensors.requestTemperatures() to issue a global temperature
  // request to all devices on the bus
  // Send the command to get temperature readings
  sensors.requestTemperatures();
  
  // make a string for assembling the data to log:
  String dataString = "";

  // read the sensor data and append to string: 
  dataString = String(id) + "," + String(sensors.getTempCByIndex(0)); // You can have more than one DS18B20 on the same bus (0 refers to the first IC on the wire).
// 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("datalog.csv", FILE_WRITE);

  // if the file is available, write to it:
  if (dataFile) {
    dataFile.println(dataString);
    dataFile.close();
    // print to the serial port too:
    Serial.println(dataString);
  }
  // if the file isn't open, pop up an error:
  else {
    Serial.println("error opening datalog.csv");
  }
  
  id++; // increase id 
  delay(5000); // wait for 5s before starting new measurement 
}