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phec/EmonLib.cpp

Created December 30, 2015 16:13
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Updated particle.io version of emonLib (photon compatible and with waveform saved)
Raw
EmonLib.cpp
/*
Emon.cpp - Library for openenergymonitor
Created by Trystan Lea, April 27 2010
GNU GPL
modified to use up to 12 bits ADC resolution (ex. Arduino Due)
by [email protected] 26.12.2013
Low Pass filter for offset removal replaces HP filter 1/1/2015 - RW
Save waveform and adapt for Particle Core/Photon 6/9/15 PHEC
*/
//#include "WProgram.h" un-comment for use on older versions of Arduino IDE
#include "EmonLib.h"
//--------------------------------------------------------------------------------------
// Sets the pins to be used for voltage and current sensors
//--------------------------------------------------------------------------------------
void EnergyMonitor::voltage(unsigned int _inPinV, double _VCAL, double _PHASECAL)
{
inPinV = _inPinV;
VCAL = _VCAL;
PHASECAL = _PHASECAL;
offsetV = ADC_COUNTS>>1;
}
void EnergyMonitor::current(unsigned int _inPinI, double _ICAL)
{
inPinI = _inPinI;
ICAL = _ICAL;
offsetI = ADC_COUNTS>>1;
}
//--------------------------------------------------------------------------------------
// Sets the pins to be used for voltage and current sensors
//--------------------------------------------------------------------------------------
void EnergyMonitor::voltage(unsigned int _inPinV, float _VCAL, float _PHASECAL)
{
inPinV = _inPinV;
VCAL = _VCAL;
PHASECAL = _PHASECAL;
offsetV = ADC_COUNTS>>1;
}
void EnergyMonitor::current(unsigned int _inPinI, float _ICAL)
{
inPinI = _inPinI;
ICAL = _ICAL;
offsetI = ADC_COUNTS>>1;
}
//--------------------------------------------------------------------------------------
// emon_calc procedure
// Calculates realPower,apparentPower,powerFactor,Vrms,Irms,kWh increment
// From a sample window of the mains AC voltage and current.
// The Sample window length is defined by the number of half wavelengths or crossings we choose to measure.
//--------------------------------------------------------------------------------------
void EnergyMonitor::calcVI(unsigned int crossings, unsigned int timeout)
{
int SupplyVoltage=3300;
//*** Photon the following variables are defined as globals for diagnostics ***
// unsigned int crossCount = 0; //Used to measure number of times threshold is crossed.
// unsigned int numberOfSamples = 0; //This is now incremented
crossCount = 0; //Used to measure number of times threshold is crossed.
numberOfSamples = 0; //This is now incremented
//-------------------------------------------------------------------------------------------------------------------------
// 1) Waits for the waveform to be close to 'zero' (mid-scale adc) part in sin curve.
//-------------------------------------------------------------------------------------------------------------------------
boolean st=false; //an indicator to exit the while loop
unsigned long start = millis(); //millis()-start makes sure it doesnt get stuck in the loop if there is an error.
while(st==false) //the while loop...
{
startV = analogRead(inPinV); //using the voltage waveform
if ((startV < (ADC_COUNTS*0.55)) && (startV > (ADC_COUNTS*0.45))) st=true; //check its within range
if ((millis()-start)>timeout) st = true;
}
//-------------------------------------------------------------------------------------------------------------------------
// 2) Main measurement loop
//-------------------------------------------------------------------------------------------------------------------------
start = millis();
while ((crossCount < crossings) && ((millis()-start)<timeout))
{
numberOfSamples++; //Count number of times looped.
lastFilteredV = filteredV; //Used for delay/phase compensation
//-----------------------------------------------------------------------------
// A) Read in raw voltage and current samples
//-----------------------------------------------------------------------------
sampleV = analogRead(inPinV); //Read in raw voltage signal
sampleI = analogRead(inPinI); //Read in raw current signal
delayMicroseconds(500); // *** Photon add delay to aid Phase correction
//-----------------------------------------------------------------------------
// B) Apply digital low pass filters to extract the 2.5 V or 1.65 V dc offset,
// then subtract this - signal is now centred on 0 counts.
//-----------------------------------------------------------------------------
offsetV = offsetV + ((sampleV-offsetV)/1024);
filteredV = sampleV - offsetV;
offsetI = offsetI + ((sampleI-offsetI)/1024);
filteredI = sampleI - offsetI;
//-----------------------------------------------------------------------------
// C) Root-mean-square method voltage
//-----------------------------------------------------------------------------
sqV= filteredV * filteredV; //1) square voltage values
sumV += sqV; //2) sum
//-----------------------------------------------------------------------------
// D) Root-mean-square method current
//-----------------------------------------------------------------------------
sqI = filteredI * filteredI; //1) square current values
sumI += sqI; //2) sum
//-----------------------------------------------------------------------------
// E) Phase calibration
//-----------------------------------------------------------------------------
phaseShiftedV = lastFilteredV + PHASECAL * (filteredV - lastFilteredV);
// *** Photon Save waveforms (use phase shifted values so phase correction can be checked)
Vwaveform[numberOfSamples%256]=uint8_t((phaseShiftedV+2048)/16);//Particle save waveform
Iwaveform[numberOfSamples%256]=uint8_t((filteredI+1024)/8); //Particle save waveform
//-----------------------------------------------------------------------------
// F) Instantaneous power calc
//-----------------------------------------------------------------------------
instP = phaseShiftedV * filteredI; //Instantaneous Power
sumP +=instP; //Sum
//-----------------------------------------------------------------------------
// G) Find the number of times the voltage has crossed the initial voltage
// - every 2 crosses we will have sampled 1 wavelength
// - so this method allows us to sample an integer number of half wavelengths which increases accuracy
//-----------------------------------------------------------------------------
/*lastVCross = checkVCross;
if (sampleV > startV) checkVCross = true;
else checkVCross = false;
if (numberOfSamples==1) lastVCross = checkVCross;
if (lastVCross != checkVCross) crossCount++;
*/
// *** Photon simplify - just count the number of positive going crossings of the filtered voltage ***
if((filteredV>0)&&(lastFilteredV<0)) crossCount++;//*** Photon This always ends on upward transition which makes for a consistent V graph
}
//-------------------------------------------------------------------------------------------------------------------------
// 3) Post loop calculations
//-------------------------------------------------------------------------------------------------------------------------
//Calculation of the root of the mean of the voltage and current squared (rms)
//Calibration coefficients applied.
double V_RATIO = VCAL *((SupplyVoltage/1000.0) / (ADC_COUNTS));
Vrms = V_RATIO * sqrt(sumV / numberOfSamples);
double I_RATIO = ICAL *((SupplyVoltage/1000.0) / (ADC_COUNTS));
Irms = I_RATIO * sqrt(sumI / numberOfSamples);
//Calculation power values
realPower = V_RATIO * I_RATIO * sumP / numberOfSamples;
apparentPower = Vrms * Irms;
powerFactor=realPower / apparentPower;
//Reset accumulators
sumV = 0;
sumI = 0;
sumP = 0;
//--------------------------------------------------------------------------------------
}
//--------------------------------------------------------------------------------------
double EnergyMonitor::calcIrms(unsigned int Number_of_Samples)
{
#if defined emonTxV3
int SupplyVoltage=3300;
#else
int SupplyVoltage = readVcc();
#endif
for (unsigned int n = 0; n < Number_of_Samples; n++)
{
sampleI = analogRead(inPinI);
// Digital low pass filter extracts the 2.5 V or 1.65 V dc offset,
// then subtract this - signal is now centered on 0 counts.
offsetI = (offsetI + (sampleI-offsetI)/1024);
filteredI = sampleI - offsetI;
// Root-mean-square method current
// 1) square current values
sqI = filteredI * filteredI;
// 2) sum
sumI += sqI;
}
double I_RATIO = ICAL *((SupplyVoltage/1000.0) / (ADC_COUNTS));
Irms = I_RATIO * sqrt(sumI / Number_of_Samples);
//Reset accumulators
sumI = 0;
//--------------------------------------------------------------------------------------
return Irms;
}
void EnergyMonitor::serialprint()
{
Serial.print(realPower);
Serial.print(' ');
Serial.print(apparentPower);
Serial.print(' ');
Serial.print(Vrms);
Serial.print(' ');
Serial.print(Irms);
Serial.print(' ');
Serial.print(powerFactor);
Serial.println(' ');
delay(100);
}
//thanks to http://hacking.majenko.co.uk/making-accurate-adc-readings-on-arduino
//and Jérôme who alerted us to http://provideyourown.com/2012/secret-arduino-voltmeter-measure-battery-voltage/
long EnergyMonitor::readVcc() {
long result;
//not used on emonTx V3 - as Vcc is always 3.3V - eliminates bandgap error and need for calibration http://harizanov.com/2013/09/thoughts-on-avr-adc-accuracy/
#if defined(__AVR_ATmega168__) || defined(__AVR_ATmega328__) || defined (__AVR_ATmega328P__)
ADMUX = _BV(REFS0) | _BV(MUX3) | _BV(MUX2) | _BV(MUX1);
#elif defined(__AVR_ATmega32U4__) || defined(__AVR_ATmega1280__) || defined(__AVR_ATmega2560__) || defined(__AVR_AT90USB1286__)
ADMUX = _BV(REFS0) | _BV(MUX4) | _BV(MUX3) | _BV(MUX2) | _BV(MUX1);
ADCSRB &= ~_BV(MUX5); // Without this the function always returns -1 on the ATmega2560 http://openenergymonitor.org/emon/node/2253#comment-11432
#elif defined (__AVR_ATtiny24__) || defined(__AVR_ATtiny44__) || defined(__AVR_ATtiny84__)
ADMUX = _BV(MUX5) | _BV(MUX0);
#elif defined (__AVR_ATtiny25__) || defined(__AVR_ATtiny45__) || defined(__AVR_ATtiny85__)
ADMUX = _BV(MUX3) | _BV(MUX2);
#endif
#if defined(__AVR__)
delay(2); // Wait for Vref to settle
ADCSRA |= _BV(ADSC); // Convert
while (bit_is_set(ADCSRA,ADSC));
result = ADCL;
result |= ADCH<<8;
result = READVCC_CALIBRATION_CONST / result; //1100mV*1024 ADC steps http://openenergymonitor.org/emon/node/1186
return result;
#elif defined(__arm__)
return (3300); //Arduino Due
#else
return (3300); //Guess that other un-supported architectures will be running a 3.3V!
#endif
}
Raw
EmonLib.h
/*
Emon.h - Library for openenergymonitor
Created by Trystan Lea, April 27 2010
GNU GPL
modified to use up to 12 bits ADC resolution (ex. Arduino Due)
by [email protected] 26.12.2013
Low Pass filter for offset removal replaces HP filter 1/1/2015 - RW
Access to V and I waveforms added 6/9/15 - PHEC
Adapted for Particle Core and Particle Photon 6/9/15 - PHEC
doubles changed to float to save RAM (not an issue with Photon)
*/
#ifndef EmonLib_h
#define EmonLib_h
#if defined(ARDUINO) && ARDUINO >= 100
#include "Arduino.h"
#else
// Particle headers
#include "application.h"
#include "math.h"
#endif
//***Photon defaults to 12 bits***
#define ADC_BITS 12
#define ADC_COUNTS (1<<ADC_BITS)
class EnergyMonitor
{
public:
void voltage(unsigned int _inPinV, float _VCAL, float _PHASECAL);
void current(unsigned int _inPinI, float _ICAL);
void voltageTX(float _VCAL, float _PHASECAL);
void currentTX(unsigned int _channel, float _ICAL);
void calcVI(unsigned int crossings, unsigned int timeout);
float calcIrms(unsigned int NUMBER_OF_SAMPLES);
void serialprint();
long readVcc();
//Useful value variables
float realPower,
apparentPower,
powerFactor,
Vrms,
Irms;
//*** Photon Expose some more useful variables ***
unsigned int numberOfSamples;
unsigned int crossCount;
uint8_t Vwaveform[256];
uint8_t Iwaveform[256];
private:
//Set Voltage and current input pins
unsigned int inPinV;
unsigned int inPinI;
//Calibration coefficients
//These need to be set in order to obtain accurate results
float VCAL;
float ICAL;
float PHASECAL;
//--------------------------------------------------------------------------------------
// Variable declaration for emon_calc procedure
//--------------------------------------------------------------------------------------
int sampleV; //sample_ holds the raw analog read value
int sampleI;
float lastFilteredV,filteredV; //Filtered_ is the raw analog value minus the DC offset
float filteredI;
float offsetV; //Low-pass filter output
float offsetI; //Low-pass filter output
float phaseShiftedV; //Holds the calibrated phase shifted voltage.
float sqV,sumV,sqI,sumI,instP,sumP; //sq = squared, sum = Sum, inst = instantaneous
int startV; //Instantaneous voltage at start of sample window.
boolean lastVCross, checkVCross; //Used to measure number of times threshold is crossed.
};
#endif
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