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Update the library
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‎MCMVoltSense.cpp‎

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/*
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MCMVoltSense.cpp - Library for Grove AC Voltage Sensor
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Author: Christopher Mendez, November 3 2022
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*/
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#include "MCMVoltSense.h"
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#if defined(ARDUINO) && ARDUINO >= 100
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#include "Arduino.h"
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#else
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#include "WProgram.h"
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#endif
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//----------------------------------------------------------------------------------
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// Sets the analog pin, calibration factors for the voltage and phase to be used
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//----------------------------------------------------------------------------------
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void MCMmeter::VoltageStp(unsigned int _analogVin, double _VoltCal, double _PhaseCal)
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{
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offsetV = ADC_COUNTS >> 1;
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PhaseCal = _PhaseCal;
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VoltCal = _VoltCal;
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analogVin = _analogVin;
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}
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//-------------------------------------------------------------------------------------------------
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// Voltage calculation from a window sample of the analog input from the Grove AC Voltage Sensor
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//-------------------------------------------------------------------------------------------------
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void MCMmeter::analogVoltage(unsigned int cycles, unsigned int timeout)
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{
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cycles = cycles/2; // Converting cycles to zero crossings
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int SupplyVoltage = boardVcc();
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unsigned int crossCount = 0; // Used to measure number of times threshold is crossed.
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unsigned int numberOfSamples = 0; // This is now incremented
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//-------------------------------------------------------------------------------------------------------------------------
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// 1) Waits for the waveform to be close to 'zero' (mid-scale adc) part in sin curve.
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//-------------------------------------------------------------------------------------------------------------------------
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unsigned long start = millis(); // timer for the timeout.
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while (1) // wait for the sine signal to zero cross, break if timeout
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{
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startV = analogRead(analogVin); // using the voltage waveform
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if ((startV < (ADC_COUNTS * 0.51)) && (startV > (ADC_COUNTS * 0.49)))
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break; // check its within range to start from here
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if ((millis() - start) > timeout)
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break;
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}
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//-------------------------------------------------------------------------------------------------------------------------
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// 2) Voltage measurement loop
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//-------------------------------------------------------------------------------------------------------------------------
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start = millis();
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while ((crossCount < cycles) && ((millis() - start) < timeout))
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{
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numberOfSamples++; // Count number of times looped.
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lastFilteredV = filteredV; // Used for delay/phase compensation
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//-----------------------------------------------------------------------------
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// A) Read in raw voltage and current samples
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//-----------------------------------------------------------------------------
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sampleV = analogRead(analogVin); // Read in raw voltage signal
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//-----------------------------------------------------------------------------
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// B) Apply digital low pass filters to extract the 2.5 V or 1.65 V dc offset,
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// then subtract this - signal is now centred on 0 counts.
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//-----------------------------------------------------------------------------
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offsetV = offsetV + ((sampleV - offsetV) / ADC_COUNTS);
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filteredV = sampleV - offsetV;
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//-----------------------------------------------------------------------------
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// C) Root-mean-square method voltage
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//-----------------------------------------------------------------------------
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sqV = filteredV * filteredV; // 1) square voltage values
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sumV += sqV; // 2) sum
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//-----------------------------------------------------------------------------
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// E) Phase calibration
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//-----------------------------------------------------------------------------
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phaseShiftedV = lastFilteredV + PhaseCal * (filteredV - lastFilteredV);
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//-----------------------------------------------------------------------------
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// G) Find the number of times the voltage has crossed the initial voltage
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// - every 2 crosses we will have sampled 1 wavelength
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// - so this method allows us to sample an integer number of half wavelengths which increases accuracy
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//-----------------------------------------------------------------------------
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lastVCross = checkVCross;
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if (sampleV > startV)
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checkVCross = true;
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else
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checkVCross = false;
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if (numberOfSamples == 1)
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lastVCross = checkVCross;
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if (lastVCross != checkVCross)
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crossCount++;
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}
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//-------------------------------------------------------------------------------------------------------------------------
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// 3) Post loop calculations
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//-------------------------------------------------------------------------------------------------------------------------
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// Calculation of the root of the mean of the voltage and current squared (rms)
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// Calibration coefficients applied.
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double V_RATIO = VoltCal * ((SupplyVoltage / 1000.0) / (ADC_COUNTS));
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Vrms = V_RATIO * sqrt(sumV / numberOfSamples);
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// Reset accumulators
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sumV = 0;
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//--------------------------------------------------------------------------------------
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}
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//-------------------------------------------------------------------------------------------------------------------------
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// Function that measures the supply voltage of the boards.
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//-------------------------------------------------------------------------------------------------------------------------
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long MCMmeter::boardVcc()
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{
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long result;
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#if defined(__AVR_ATmega168__) || defined(__AVR_ATmega328__) || defined(__AVR_ATmega328P__)
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ADMUX = _BV(REFS0) | _BV(MUX3) | _BV(MUX2) | _BV(MUX1);
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#elif defined(__AVR_ATmega644__) || defined(__AVR_ATmega644P__) || defined(__AVR_ATmega1284__) || defined(__AVR_ATmega1284P__)
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ADMUX = _BV(REFS0) | _BV(MUX4) | _BV(MUX3) | _BV(MUX2) | _BV(MUX1);
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#elif defined(__AVR_ATmega32U4__) || defined(__AVR_ATmega1280__) || defined(__AVR_ATmega2560__) || defined(__AVR_AT90USB1286__)
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ADMUX = _BV(REFS0) | _BV(MUX4) | _BV(MUX3) | _BV(MUX2) | _BV(MUX1);
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ADCSRB &= ~_BV(MUX5); // Without this the function always returns -1 on the ATmega2560
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#elif defined(__AVR_ATtiny24__) || defined(__AVR_ATtiny44__) || defined(__AVR_ATtiny84__)
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ADMUX = _BV(MUX5) | _BV(MUX0);
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#elif defined(__AVR_ATtiny25__) || defined(__AVR_ATtiny45__) || defined(__AVR_ATtiny85__)
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ADMUX = _BV(MUX3) | _BV(MUX2);
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#endif
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#if defined(__AVR__)
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delay(2); // Wait for the reference voltage to stabilize
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ADCSRA |= _BV(ADSC); // Convert
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while (bit_is_set(ADCSRA, ADSC))
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;
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result = ADCL;
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result |= ADCH << 8;
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result = READVCC_CALIBRATION_CONST / result; // 1100mV*1024 ADC steps
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return result;
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#elif defined(__arm__)
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return (3300); // Arduino Due
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#else
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return (3300); // Assuming other architectures works with 3.3V!
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#endif
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}

‎MCMVoltSense.h‎

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/*
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MCMVoltSense.cpp - Library for Grove AC Voltage Sensor
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Author: Christopher Mendez, November 3 2022
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*/
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#ifndef MCMVoltSense_h
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#define MCMVoltSense_h
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#if defined(ARDUINO) && ARDUINO >= 100
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#include "Arduino.h"
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#else
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#include "WProgram.h"
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#endif
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// define theoretical vref calibration constant for use in boardVcc()
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// 1100mV*1024 ADC steps
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// override in your code with value for your specific AVR chip
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#ifndef READVCC_CALIBRATION_CONST
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#define READVCC_CALIBRATION_CONST 1126400L
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#endif
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// to enable 12-bit ADC resolution on Arduino Due,
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// include the following line in main sketch inside setup() function:
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// analogReadResolution(ADC_BITS);
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// otherwise will default to 10 bits, as in regular Arduino-based boards.
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#if defined(__arm__)
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#define ADC_BITS 12
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#else
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#define ADC_BITS 10
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#endif
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#define ADC_COUNTS (1<<ADC_BITS)
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class MCMmeter
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{
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public:
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void VoltageStp(unsigned int _analogVin, double _VoltCal, double _PhaseCal);
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void analogVoltage(unsigned int cycles, unsigned int timeout);
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long boardVcc();
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//Useful value variables
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double Vrms;
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private:
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//Set Voltage and current input pins
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unsigned int analogVin;
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//Calibration coefficients
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//These need to be set in order to obtain accurate results
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double VoltCal;
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double PhaseCal;
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//--------------------------------------------------------------------------------------
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// Variable declaration
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//--------------------------------------------------------------------------------------
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int sampleV; //sample holds the raw analog read value
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double lastFilteredV,filteredV; //Filtered is the raw analog value minus the DC offset
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double offsetV; //Low-pass filter output
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double phaseShiftedV; //Holds the calibrated phase shifted voltage.
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double sqV,sumV; //sq = squared, sum = Sum
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int startV; //Instantaneous voltage at start of sample window.
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boolean lastVCross, checkVCross; //Used to measure number of times threshold is crossed.
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};
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#endif

‎examples/VoltageSensing/VoltageSensing.ino‎

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#include "MCMVoltSense.h" // Include MCM Volt Sense Library
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MCMmeter meter; // Create an instance
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void setup() {
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Serial.begin(115200);
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meter.VoltageStp(A1, 523.56, 1.7); // Voltage: input pin, calibration, phase_shift
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}
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void loop() {
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meter.analogVoltage(40,2000); // Measure the AC voltage. Arguments = (# of AC cycles, timeout)
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float Vrms = meter.Vrms; // Save the RMS Voltage into a variable.
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Serial.print("Voltage: ");
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Serial.print(Vrms,2);
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Serial.println(" V");
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delay(2000);
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}

‎keywords.txt‎

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#######################################
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# Syntax Coloring Map
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#######################################
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#######################################
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# Datatypes (KEYWORD1)
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#######################################
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MCMmeter KEYWORD1
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#######################################
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# Methods and Functions (KEYWORD2)
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#######################################
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VoltageStp KEYWORD2
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analogVoltage KEYWORD2
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boardVcc KEYWORD2
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######################################
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# Constants (LITERAL1)
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#######################################
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Vrms LITERAL1

‎library.json‎

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{
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"name": "MCMVoltSense",
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"keywords": "voltage, measurement, energy",
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"description": "AC Voltage Measurement Library",
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"version": "0.0.1",
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"repository":
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{
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"type": "git",
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"url": "https://github.com/mcmchris/mcm-grove-voltage-sensor.git"
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},
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"frameworks": "arduino",
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"platforms":
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[
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"atmelavr",
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"atmelsam"
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]
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}

‎library.properties‎

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name=MCMVoltSense
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version=0.0.1
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author=mcmchris
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maintainer=mcmchris
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sentence=Voltage Measurement Library
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paragraph=Voltage Measurement Library
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category=Sensors
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url=https://github.com/mcmchris/mcm-grove-voltage-sensor.git
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architectures=*

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