/*
  SD card datalogger
 
 This example shows how to log data from three analog sensors 
 to an SD card using the SD library.
 	
 The circuit:
 * SD card attached to SPI bus as follows:
 ** UNO:  MOSI - pin 11, MISO - pin 12, CLK - pin 13, CS - pin 4 (CS pin can be changed)
  and pin #10 (SS) must be an output
 ** Mega:  MOSI - pin 51, MISO - pin 50, CLK - pin 52, CS - pin 4 (CS pin can be changed)
  and pin #52 (SS) must be an output
 ** Leonardo: Connect to hardware SPI via the ICSP header
 		Pin 4 used here for consistency with other Arduino examples
 
original code was created on 24 Nov 2010 and  modified 9 Apr 2012 by Tom Igoe
I (Debasish Dutta) was again modified for my energy monitoring requirement on 14/01/14

 
 This example code is in the public domain.
 	 
 */

#include <SD.h>

// On the Ethernet Shield, CS is pin 4. Note that even if it's not
// used as the CS pin, the hardware CS pin (10 on most Arduino boards,
// 53 on the Mega) must be left as an output or the SD library
// functions will not work.
const int chipSelect = 4;

File dataFile;


float sample1=0; // for voltage
float sample2=0; // for current
float voltage=0.0;
float val; // current callibration
float actualval; // read the actual current from ACS 712
float amps=0.0;
float totamps=0.0; 
float avgamps=0.0;
float amphr=0.0;
float watt=0.0;
float energy=0.0; 

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


  Serial.print("Initializing SD card...");
  // make sure that the default chip select pin is set to
  // output, even if you don't use it:
  pinMode(SS, OUTPUT);
  
  // 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.");
  
  // Open up the file we're going to log to!
  dataFile = SD.open("energy.txt", FILE_WRITE);
  if (! dataFile) {
    Serial.println("error opening energy.txt");
    // Wait forever since we cant write data
    while (1) ;
  }
}

void loop()

{
   
 long milisec = millis(); // calculate time in milisec
 long time=milisec/1000; // convert time to sec

 ///////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////// 
                      /// taking 150 samples from sensors with a inerval of 2sec and then average the samples data collected
  for(int i=0;i<150;i++)
  {
    sample1+=analogRead(A2);  //read the voltage from the sensor
    sample2+=analogRead(A3); //read the current from sensor
    delay(2);
  }
   sample1=sample1/150; 
   sample2=sample2/150;
   
  ////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////// 
                                                 /////voltage calculation//////////////////////
  
   voltage=4.669*2*sample1/1000; //  callibration // 3.25 from voltage div is eqv 696 in A0 reading 
                                 // multiply 2 to get actual voltage//  I used two 1k resistor to read 6.36v battery volt
                                 
    //////////////////////////////////////////////// current calculation //////////////////////
 val =(5.0*sample2)/1024.0; 
 actualval =val-2.5; // offset voltage is 2.5v 
 amps =actualval*10;// 10 is multiplied as 100mv/A ( from data sheet )
 totamps=totamps+amps; // total amperes 
 avgamps=totamps/time; // average amperess
 amphr=(avgamps*time);  // ampere hour
 watt =voltage*amps;    // power=voltage*current
 energy=(watt*time)/3600;      // energy = power*timein Watt-sec ///again convert to Watt-Hr by dividing 3600sec
 
  ////////////////////////////////////////////////////////
  // make a string for assembling the data to log:
String dataString = "";
int parameter[4]={voltage,amps,watt,energy}; // here parameters are power,energy,watt-hour and current
  // read 4 parameters and append to the string:
  for (int i = 0; i < 4; i++) 
  {
    int sensor = parameter[i];
    dataString += String(sensor);
    if (i < 4) 
    {
      dataString += ","; 
    }
  }

  dataFile.println(dataString);

  // print to the serial port too:
  Serial.println(dataString);
  
  // The following line will 'save' the file to the SD card after every
  // line of data - this will use more power and slow down how much data
  // you can read but it's safer! 
  // If you want to speed up the system, remove the call to flush() and it
  // will save the file only every 512 bytes - every time a sector on the 
  // SD card is filled with data.
  dataFile.flush();
  
  // Take 1 measurement every 500 milliseconds
  delay(500);
}