#include "DHT.h"

#define DHTPIN 2     
#define DHTTYPE DHT22   // DHT 22  (AM2302), AM2321
#include <SPI.h>
#include <SD.h>

const int chipSelect = 4;

DHT dht(DHTPIN, DHTTYPE);

void setup() {
  Serial.begin(115200);

  dht.begin();
  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() {
  float temperature = dht.readTemperature();
  float humidity = dht.readHumidity();

  // Check if any reads failed and exit early (to try again).
  if (isnan(temperature) || isnan(humidity)) {
    Serial.println(F("Failed to read from DHT sensor!"));
    return;
  }
  // Wait a few seconds between measurements.
  delay(2000);
  String dataString = "";

  // read three sensors and append to the string:
    dataString += "Humidity: ";
    dataString += humidity;
    dataString += "%  Temperature: ";
    dataString += temperature;
    dataString += "°C ";

  // 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.txt", 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.txt");
  }
}