Sketch: #5

I need to work on the formatting of the code block, but the base is there for now.

                ---- Log it to an SD card

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

//Constants
#define DHTPIN 7     // what pin we're connected to
#define DHTTYPE DHT22   // DHT 22  (AM2302)
DHT dht(DHTPIN, DHTTYPE); //// Initialize DHT sensor for normal 16mhz Arduino

//Variables
const int chipSelect = 4;
int chk;
float hum;  //Stores humidity value
float temp; //Stores temperature value
float fahrenheit; //Stores fahrenheit temp
String JSONSensor = "";

void setup() {
  // Open serial communications and wait for port to open:
  Serial.begin(9600);
  dht.begin();
  while (!Serial) {
    ; // wait for serial port to connect. Needed for native USB port only
  }


  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() {
  //get sensor data
  do_temp(); 
  delay(1000);

  // 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(JSONSensor);
    dataFile.close();
    // print to the serial port too:
    Serial.println("Wrote: " + JSONSensor);
  }
  // if the file isn't open, pop up an error:
  else {
    Serial.println("error opening datalog.txt");
  }
}

void do_temp(){
    //Read data and store it to variables hum and temp
    hum = dht.readHumidity();
    temp= dht.readTemperature();
    fahrenheit = 1.8 * temp + 32;
      
    // make a string for assembling the data to log:
    String dataString = "{ \"humidity\": "+ String(hum) + ", ";
    dataString +=  "\"Celsius\": "+ String(temp) + ", ";
    dataString += "\"Fahrenheit\": "+ String(fahrenheit) + "}";

    JSONSensor = dataString;
}