#include <SPI.h>
#include <DHT.h>
#include <SD.h>

#define DHTPIN 2          // connect "DHT22 SDA" to "Arduino D2"
#define DHTTYPE DHT22     // Specify DHT22 sensor type

#define CSPIN 10          //connect "SDcards CS" to "Arduino D10"

DHT dht(DHTPIN, DHTTYPE);

File dataFile;

void setup() {
  Serial.begin(9600);
  dht.begin();

  // Initialising the SD card
  if (!SD.begin(CSPIN)) {
    Serial.println("SD card initialisation failed.");
    return;
  }
  Serial.println("SD card has been initialised.");
}

void loop() {
  // Read temperature and humidity
  float h = dht.readHumidity();
  float t = dht.readTemperature();

  // Check that the data has been successfully read
  if (isnan(h) || isnan(t)) {
    Serial.println("Sensor readings failed!");
    return;
  }

  // show data
  Serial.print("temperature: ");
  Serial.print(t);
  Serial.print("°C ");
  Serial.print("humidity: ");
  Serial.print(h);
  Serial.println("%");

  // Save data to SD card
  dataFile = SD.open("datalog.txt", FILE_WRITE);

  if (dataFile) {
    dataFile.print("temperature: ");
    dataFile.print(t);
    dataFile.print("°C ");
    dataFile.print("humidity: ");
    dataFile.print(h);
    dataFile.println("%");
    dataFile.close();
    Serial.println("Data has been saved.");
  } else {
    Serial.println("Could not open data file.");
  }

  delay(1000); // wait for 1sec
}