Arduino Temperature and Humidity Logger using Adafruit SD Shield and DHT22

sketch.ino

// log DHT sensor readings to SD card
#include "DHT.h"
#include <SD.h>
#include <Wire.h>
#include "RTClib.h"

RTC_DS1307 RTC;

// how many milliseconds between grabbing data and logging it. 1000 ms is once a second
#define LOG_INTERVAL  60000 // mills between entries (reduce to take more/faster data)

#define ECHO_TO_SERIAL   1 // echo data to serial port

#define DHTPIN 3     // what pin we're connected to

// Uncomment whatever type you're using!
//#define DHTTYPE DHT11   // DHT 11 
#define DHTTYPE DHT22   // DHT 22  (AM2302)
//#define DHTTYPE DHT21   // DHT 21 (AM2301)

// Connect pin 1 (on the left) of the sensor to +5V
// Connect pin 2 of the sensor to whatever your DHTPIN is
// Connect pin 4 (on the right) of the sensor to GROUND
// Connect a 10K resistor from pin 2 (data) to pin 1 (power) of the sensor

DHT dht(DHTPIN, DHTTYPE);

// select 10 for adafruit shield
const int chipSelect = 10;

// create file to log to
File logfile;

void setup() {
  Serial.begin(9600); 
  
  Serial.print("Initializing SD card...");
  // make sure that the default chip select pin is set to
  // output, even if you don't use it:
  pinMode(10, OUTPUT);
  
  if (!SD.begin(chipSelect)) {
    Serial.println("Card failed, or not present");
    // don't do anything more:
    return;
  }
  Serial.println("card initialized.");
  
  // create a new file
  char filename[] = "LOGGER00.CSV";
  for (uint8_t i = 0; i < 100; i++) {
    filename[6] = i/10 + '0';
    filename[7] = i%10 + '0';
    if (! SD.exists(filename)) {
      // only open a new file if it doesn't exist
      logfile = SD.open(filename, FILE_WRITE); 
      break;  // leave the loop!
    }
  }
  
  if (! logfile) {
    Serial.println("could not create file");
  }
  
  Serial.print("Logging to: ");
  Serial.println(filename);

  // connect to RTC
  Wire.begin();  
  if (!RTC.begin()) {
    logfile.println("RTC failed");
#if ECHO_TO_SERIAL
    Serial.println("RTC failed");
#endif  //ECHO_TO_SERIAL
  }
  
  logfile.println("millis,datetime,rh,temp_c,temp_f,sat_vapor_density,vapor_density");    
#if ECHO_TO_SERIAL
  Serial.println("millis,datetime,rh,temp_c,temp_f,sat_vapor_density,vapor_density");
#endif //ECHO_TO_SERIAL
  dht.begin();
}

void loop() {
  DateTime now;
  
  delay((LOG_INTERVAL -1) - (millis() % LOG_INTERVAL));
  
  String dataString = "";
  
  // fetch the time
  now = RTC.now();
  // log time
  logfile.print(now.unixtime()); // seconds since 1/1/1970
  logfile.print(",");
  if (now.month() < 10) {
    logfile.print(0, DEC);
  }
  logfile.print(now.month(), DEC);
  logfile.print("/");
  if (now.day() < 10) {
    logfile.print(0, DEC);
  }
  logfile.print(now.day(), DEC);
  logfile.print("/");
  logfile.print(now.year(), DEC);
  logfile.print(" ");
  if (now.hour() < 10) {
    logfile.print(0, DEC);
  }
  logfile.print(now.hour(), DEC);
  logfile.print(":");
  if (now.minute() < 10) {
    logfile.print(0, DEC);
  }
  logfile.print(now.minute(), DEC);
  logfile.print(":");
  if (now.second() < 10) {
    logfile.print(0, DEC);
  }
  logfile.print(now.second(), DEC);
#if ECHO_TO_SERIAL
  Serial.print(now.unixtime()); // seconds since 1/1/1970
  Serial.print(",");
  if (now.month() < 10) {
    Serial.print(0, DEC);
  }
  Serial.print(now.month(), DEC);
  Serial.print("/");
  if (now.day() < 10) {
    Serial.print(0, DEC);
  }
  Serial.print(now.day(), DEC);
  Serial.print("/");
  Serial.print(now.year(), DEC);
  Serial.print(" ");
  if (now.hour() < 10) {
    Serial.print(0, DEC);
  }  
  Serial.print(now.hour(), DEC);
  Serial.print(":");
  if (now.minute() < 10) {
    Serial.print(0, DEC);
  }
  Serial.print(now.minute(), DEC);
  Serial.print(":");
  if (now.second() < 10) {
    Serial.print(0, DEC);
  }
  Serial.print(now.second(), DEC);
#endif //ECHO_TO_SERIAL
  
  // Reading temperature or humidity takes about 250 milliseconds!
  // Sensor readings may also be up to 2 seconds 'old' (its a very slow sensor)
  float h = dht.readHumidity(); // relative humidity, %
  float t_c = dht.readTemperature(); // air temp, degC
  float t_f = t_c*9.0/5.0 + 32.0; // air temp, degF
  float svd; // saturation vapor density, g/m3
  float vd; // vapor density, g/m3

  // check if returns are valid, if they are NaN (not a number) then something went wrong!
  if (isnan(t_c) || isnan(h)) {
    Serial.println("Failed to read from DHT");
  } else {
    svd = 5.018 + 0.32321*t_c + 8.1847e-3*pow(t_c,2) + 3.1243e-4*pow(t_c,3);
    vd = h/100*svd;
    logfile.print(",");    
    logfile.print(h, 2);
    logfile.print(",");    
    logfile.print(t_c, 2);
    logfile.print(",");    
    logfile.print(t_f, 2);
    logfile.print(",");    
    logfile.print(svd, 4);
    logfile.print(",");    
    logfile.print(vd, 4);

#if ECHO_TO_SERIAL
    Serial.print(",");   
    Serial.print(h, 2);
    Serial.print(",");    
    Serial.print(t_c, 2);
    Serial.print(",");    
    Serial.print(t_f, 2);
    Serial.print(",");    
    Serial.print(svd, 4);
    Serial.print(",");    
    Serial.print(vd, 4);
#endif //ECHO_TO_SERIAL
  }
  
  logfile.println();
#if ECHO_TO_SERIAL
  Serial.println();
#endif // ECHO_TO_SERIAL

  // flush to file
  logfile.flush();
}

have simulate error
i need library ,please

need to #include <SPI.h>