#include "DHT.h"
#include "SPI.h" //for the SD card module
#include <SD.h>


#define DHTPIN 2     
// uncomment whatever type you're using
//#define DHTTYPE DHT11   // DHT 11 
//#define DHTTYPE DHT22   // DHT 22  (AM2302)
//#define DHTTYPE DHT21   // DHT 21 (AM2301)
#define DHTTYPE DHT22   // DHT 22  (AM2302), AM2321
const int chipSelect = 4; 

// Create a file to store the data
File myFile;

DHT dht(DHTPIN, DHTTYPE);

void setup() {
  Serial.begin(115200);
  Serial.println(F("DHT22 example!"));

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

  if(!SD.begin(chipSelect)) {
    Serial.println("initialization failed!");
    return;
  }
  Serial.println("initialization done.");
    
  //open file
  myFile=SD.open("DATA.txt", FILE_WRITE);

  // if the file opened ok, write to it:
  if (myFile) {
    Serial.println("File opened ok");
    // print the headings for our data
    myFile.println("Date,Time,Temperature ºC");
  }
  myFile.close();
}

void loggingTemperature() {
  // Reading temperature or humidity takes about 250 milliseconds!
  // Sensor readings may also be up to 2 seconds 'old' (its a very slow sensor)
  // Read temperature as Celsius
  float t = dht.readTemperature();
  // Read temperature as Fahrenheit
  //float f = dht.readTemperature(true);
  
  // Check if any reads failed and exit early (to try again).
  if  (isnan(t) /*|| isnan(f)*/) {
    Serial.println("Failed to read from DHT sensor!");
    return;
  }
  
  //debugging purposes
  Serial.print("Temperature: "); 
  Serial.print(t);
  Serial.println(" *C");
  //Serial.print(f);
  //Serial.println(" *F\t"); 
  
  myFile = SD.open("DATA.txt", FILE_WRITE);
  if (myFile) {
    Serial.println("open with success");
    myFile.print(t);
    myFile.println(",");
  }
  myFile.close();
}

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;
  }

  Serial.print(F("Humidity: "));
  Serial.print(humidity);
  Serial.print(F("%  Temperature: "));
  Serial.print(temperature);
  Serial.println(F("°C "));

  // Wait a few seconds between measurements.
  delay(2000);
  loggingTemperature();
  delay(5000);
}