// Code developed by Dr Kris Chan & Dr Bruce Main, King's College London 20.10.2018 //
//////////////////////////////////////////////////////////////////////////////////////

/* LIBRARIES */
#include <SPI.h>             //SPI communication library (for clock & SD card)
#include <SdFat.h>           //SD library. Need this library? https://github.com/greiman/SdFat


/* CONSTANTS */
int count = 0;
unsigned int wADC;        //Arduino internal temperature call
int CS=10;
//SD HOUSEKEEPING
SdFat sd;
SdFile file;
char newfile[] = "MyFileName.csv";      //name of file


/* SETUP */
void setup() {
Serial.begin(9600);
Serial.println("setup start"); 
 
 while (!sd.begin(CS, SPI_HALF_SPEED)) {}             //SD card housekeeping
  file.open(newfile, O_WRITE | O_CREAT | O_APPEND);
  file.close();
  
Serial.println("setup end"); 
 delay(100); 
 }

/* LOOP */
void loop() {
Serial.println("loop"); 
  delay(1000);
  count++;
  GetTemp();

//data written to SD:
      String dataString = "";
      dataString += count;
      dataString += ",";
      dataString += wADC;
      Serial.println(dataString);
      Serial.println("");
      delay(50);


       while (!sd.begin(CS,SPI_HALF_SPEED)) {
        
        } // initialises SD card again - for when sd card is removed for data
       
       file.open(newfile, O_WRITE | O_APPEND); //Opens the file
       delay(5);
       file.println(dataString); //prints data string to the file
       delay(5);
       file.close(); //closes the file
       delay(20);
}

/* GET PROCESSOR TEMPERATURE SUBROUTINE */
double GetTemp(void)
{
  ADMUX = (_BV(REFS1) | _BV(REFS0) | _BV(MUX3));
  ADCSRA |= _BV(ADEN);  
  delay(20);          
  ADCSRA |= _BV(ADSC);  
  while (bit_is_set(ADCSRA,ADSC));
  wADC = ADCW;
}