Luminosity Sensor- TSL2561 Breakout

#include <SFE_TSL2561.h>
#include <Wire.h>

// Create an SFE_TSL2561 object, here called "light":

SFE_TSL2561 light;

// Global variables:

boolean gain;     // Gain setting, 0 = X1, 1 = X16;
unsigned int ms;  // Integration ("shutter") time in milliseconds

void setup()
{
  // Initialize the Serial port:

  Serial.begin(9600);
  Serial.println("TSL2561 example sketch");

  // Initialize the SFE_TSL2561 library

  // You can pass nothing to light.begin() for the default I2C address (0x39),
  // or use one of the following presets if you have changed
  // the ADDR jumper on the board:

  // TSL2561_ADDR_0 address with '0' shorted on board (0x29)
  // TSL2561_ADDR   default address (0x39)
  // TSL2561_ADDR_1 address with '1' shorted on board (0x49)

   light.begin();

  // Get factory ID from sensor:
  // (Just for fun, you don't need to do this to operate the sensor)

  unsigned char ID;

  if (light.getID(ID))
  {
    Serial.print("Got factory ID: 0X");
    Serial.print(ID,HEX);
    Serial.println(", should be 0X5X");
  }
  // Most library commands will return true if communications was successful,
  // and false if there was a problem. You can ignore this returned value,
  // or check whether a command worked correctly and retrieve an error code:
  else
  {
    byte error = light.getError();
    printError(error);
  }
  gain = 0;

  // If time = 0, integration will be 13.7ms
  // If time = 1, integration will be 101ms
  // If time = 2, integration will be 402ms
  // If time = 3, use manual start / stop to perform your own integration

  unsigned char time = 2;

  // setTiming() will set the third parameter (ms) to the
  // requested integration time in ms (this will be useful later):

  Serial.println("Set timing...");
  light.setTiming(gain,time,ms);

  // To start taking measurements, power up the sensor:

  Serial.println("Powerup...");
  light.setPowerUp();

  // The sensor will now gather light during the integration time.
  // After the specified time, you can retrieve the result from the sensor.
  // Once a measurement occurs, another integration period will start.
}

void loop()
{
  delay(ms);
  unsigned int data0, data1;

  if (light.getData(data0,data1))
  {
    // getData() returned true, communication was successful

    Serial.print("data0: ");
    Serial.print(data0);
    Serial.print(" data1: ");
    Serial.print(data1); 
    double lux;    // Resulting lux value
    boolean good;  // True if neither sensor is saturated

    // Perform lux calculation:

    good = light.getLux(gain,ms,data0,data1,lux);

    // Print out the results:

    Serial.print(" lux: ");
    Serial.print(lux);
    if (good) Serial.println(" (good)"); else Serial.println(" (BAD)");
  }
  else
  {
    // getData() returned false because of an I2C error, inform the user.

    byte error = light.getError();
    printError(error);
  }
}

void printError(byte error)
  // If there's an I2C error, this function will
  // print out an explanation.
{
  Serial.print("I2C error: ");
  Serial.print(error,DEC);
  Serial.print(", ");

  switch(error)
  {
    case 0:
      Serial.println("success");
      break;
    case 1:
      Serial.println("data too long for transmit buffer");
      break;
    case 2:
      Serial.println("received NACK on address (disconnected?)");
      break;
    case 3:
      Serial.println("received NACK on data");
      break;
    case 4:
      Serial.println("other error");
      break;
    default:
      Serial.println("unknown error");
  }
}