Archived Forum

Hi

I just wanted to post the code for my Energy Monitor, it is based on Trystan Lea and Eric Sandeen code. i just added a LCD 16x2 menu and a way to storage data in a SD card. For this I used Adafruit Loggin shield, http://www.adafruit.com/products/243 and seedstudio 100 Amp CT. I hope its useful, if you need more informatin please ask. Thanks a lot for your support, this project was very fun to do and I hope to keep evolving it, maybe next phase will be to stream the information to a web server installed in a modiffied apple tv 1 (the only computer that is on all the time at home)

//Basic energy monitoring sketch
//Based on design by: Trystan Lea, Eric Sandeen
//Licenced under GNU General Public Licence
// openenergymonitor.org
// Patricio Duenas

//Sketch measures voltage and current.
//and then calculates useful values like real power,
//apparent power, powerfactor, Vrms, Irms.

// Connections:
// rs (LCD pin 4) to Arduino pin 9
// rw (LCD pin 5) to Arduino pin 8
// enable (LCD pin 6) to Arduino pin 7
// Arduino pin 6 goes to pushbutton for menu
// LCD pins d4, d5, d6, d7 to Arduino pins 5, 4, 3, 2

#include <LiquidCrystal.h>
#include <Wire.h>
#include "RTClib.h"
#include <SD.h>

//initialize lcd
LiquidCrystal lcd(9, 8, 7, 5, 4, 3, 2);
int menupin = 6;
int menusum = 0;
int menu = 0;

//Setup variables
int numberOfSamples = 3000;

//Set Voltage and current input pins
int inPinV = 2;
int inPinI = 1;

//define RTC object
RTC_DS1307 RTC;

//Sanity check calibration method thanks to Eric Sandeen http://sandeen.net/wordpress
//See discussion here: http://openenergymonitor.org/emon/node/59
//Enter the values of your setup below

// Voltage is reduced both by wall xfmr & voltage divider
#define AC_WALL_VOLTAGE        130
#define AC_ADAPTER_VOLTAGE     3.63
// Ratio of the voltage divider in the circuit
#define AC_VOLTAGE_DIV_RATIO   3.3859
// CT: Voltage depends on current, burden resistor, and turns
#define CT_BURDEN_RESISTOR    88
#define CT_TURNS              3030

//Calibration coeficients
//These need to be set in order to obtain accurate results
//Set the above values first and then calibrate futher using normal calibration method described on how to build it page.
double VCAL = 1.111;
double ICAL = 0.62;
double PHASECAL = 2;

// Initial gueses for ratios, modified by VCAL/ICAL tweaks
#define AC_ADAPTER_RATIO       (AC_WALL_VOLTAGE / AC_ADAPTER_VOLTAGE)
double V_RATIO = AC_ADAPTER_RATIO * AC_VOLTAGE_DIV_RATIO * 5 / 1024 * VCAL;
double I_RATIO = (long double)CT_TURNS / CT_BURDEN_RESISTOR * 5 / 1024 * ICAL;

//Sample variables
int lastSampleV,lastSampleI,sampleV,sampleI;

//Filter variables
double lastFilteredV, lastFilteredI, filteredV, filteredI;
double filterTemp;

//Stores the phase calibrated instantaneous voltage.
double shiftedV;

//Power calculation variables
double sqI,sqV,instP,sumI,sumV,sumP;

//Useful value variables
double realPower,
       apparentPower,
       powerFactor,
       Vrms,
       Irms;

//SD writing related variables
const int chipSelect = 10;   //SD CS for adafruit shield
File logfile;   // the logging file
#define SYNC_INTERVAL 60000   //interval to write data to SD, here is set to 1 munite in miliseconds
                              //minus 1 sec for the V and I sampling time 
uint32_t syncTime = 0;  //time of last sync

void setup()
{
  Serial.begin(57600);
  Wire.begin();
  RTC.begin();
  RTC.adjust(DateTime(__DATE__, __TIME__));  //set RTC to computer's clock at the time of compilation
 
  // make sure that the default chip select pin is set to
  // output, even if you don't use it:
  pinMode(10, OUTPUT);
  pinMode(menupin, INPUT);
  // see if the card is present and can be initialized:
  lcd.begin(16,2);
  lcd.clear();
  lcd.setCursor(0,0);
  if (!SD.begin(chipSelect)) {
    lcd.print("Card failed, or");
    lcd.setCursor(0,1);
    lcd.print("not present");
    delay(5000);
    lcd.clear();
  }else{
  lcd.print("card initialized");
  delay(2000);
  // create a new file
  char filename[] = "LOGGER00.CSV";          //Every time the Arduino starts, we will create
  for (uint8_t i = 0; i < 100; i++) {        //a new file named LOGGERnn.csv
    filename[6] = i/10 + '0';
    filename[7] = i%10 + '0';
    if (! SD.exists(filename)) {
     // only open a new file if it doesn't exist
     logfile = SD.open(filename, FILE_WRITE);
     break;  // leave the loop!
    }
  }
  logfile.println("date,time,realPower,apparentPower,powerFactor,Vrms,Irms");  //this is the header of the csv file
  }
}

void loop()
{
menusum = digitalRead(menupin);
if ( menusum == HIGH) {
  menu = menu+1;
}
for (int n=0; n<numberOfSamples; n++)
{
   //Used for offset removal
   lastSampleV=sampleV;
   lastSampleI=sampleI;
  
   //Read in voltage and current samples.  
   sampleV = analogRead(inPinV);
   sampleI = analogRead(inPinI);
  
   //Used for offset removal
   lastFilteredV = filteredV;
   lastFilteredI = filteredI;
 
   //Digital high pass filters to remove 2.5V DC offset.
   filteredV = 0.996*(lastFilteredV+sampleV-lastSampleV);
   filteredI = 0.996*(lastFilteredI+sampleI-lastSampleI);
  
   //Phase calibration goes here.
   shiftedV = lastFilteredV + PHASECAL * (filteredV - lastFilteredV);
 
   //Root-mean-square method voltage
   //1) square voltage values
   sqV= filteredV * filteredV;
   //2) sum
   sumV += sqV;
  
   //Root-mean-square method current
   //1) square current values
   sqI = filteredI * filteredI;
   //2) sum
   sumI += sqI;

   //Instantaneous Power
   instP = shiftedV * filteredI;
   //Sum
   sumP +=instP;
}

//Calculation of the root of the mean of the voltage and current squared (rms)
//Calibration coeficients applied.
Vrms = V_RATIO*sqrt(sumV / numberOfSamples);
Irms = I_RATIO*sqrt(sumI / numberOfSamples);

//Calculation power values
realPower = V_RATIO*I_RATIO*sumP / numberOfSamples;
apparentPower = Vrms * Irms;
powerFactor = realPower / apparentPower;

//output to serial  i, v, real p
Serial.print(Vrms);
Serial.print("  ");
Serial.print(Irms);
Serial.print("  ");
Serial.println(realPower);

//output to lcd
DateTime now = RTC.now();

if (menu == 0) {
lcd.clear();                  // start with a blank screen
lcd.setCursor(4,0);           // set cursor to column 0, row 0 (the first row)
lcd.print(now.day(), DEC);
lcd.print("/");
lcd.print(now.month(), DEC);
lcd.print("/");
lcd.print(now.year(), DEC);
lcd.setCursor(5,1);
lcd.print(now.hour(), DEC);
lcd.print(":");
if(now.minute() < 10){   //little trick to print 0 to 9 minutes
  lcd.print("0");
}
lcd.print(now.minute(), DEC); 
}

if (menu == 1){
lcd.clear();                  // start with a blank screen
lcd.setCursor(0,0);           // set cursor to column 0, row 0 (the first row)
lcd.print(realPower);
lcd.setCursor(6,0);           //main menu, will have to change to a more complex one
lcd.print("Real Power");
lcd.setCursor(0,1);
lcd.print(Vrms);
lcd.setCursor(4,1);
lcd.print("Vrms");
lcd.setCursor(9,1);
lcd.print(Irms);
lcd.setCursor(12,1);
lcd.print("Irms");
}

if (menu == 2){
lcd.clear();                  // start with a blank screen
lcd.setCursor(0,0);           // set cursor to column 0, row 0 (the first row)
lcd.print(powerFactor);
lcd.setCursor(6,0);           //main menu, will have to change to a more complex one
lcd.print("Pwr Factor");
lcd.setCursor(0,1);
lcd.print(apparentPower);
lcd.setCursor(7,1);
lcd.print("Aprnt Pwr");
}

if (menu > 2){
    menu = 0;
  }
 
//Reset accumulators
sumV = 0;
sumI = 0;
sumP = 0;

//Save data to disk once every minute
if ((millis() - syncTime) < SYNC_INTERVAL) return;
syncTime = millis();

//write data to SD
  logfile.print(now.year(), DEC);
  logfile.print("/");
  logfile.print(now.month(), DEC);
  logfile.print("/");
  logfile.print(now.day(), DEC);
  logfile.print(" ");
  logfile.print(",");
  logfile.print(now.hour(), DEC);
  logfile.print(":");
  logfile.print(now.minute(), DEC);
  logfile.print(":");
  logfile.print(now.second(), DEC);
  logfile.print(", ");   
  logfile.print(realPower);
  logfile.print(", ");   
  logfile.print(apparentPower);
  logfile.print(", ");   
  logfile.print(powerFactor);
  logfile.print(", ");   
  logfile.print(Vrms);
  logfile.print(", ");   
  logfile.println(Irms);
  logfile.flush();

}