Update the library

MCMVoltSense.cpp

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+/*
+  MCMVoltSense.cpp - Library for Grove AC Voltage Sensor
+  Author: Christopher Mendez, November 3 2022
+*/
+
+#include "MCMVoltSense.h"
+
+#if defined(ARDUINO) && ARDUINO >= 100
+#include "Arduino.h"
+#else
+#include "WProgram.h"
+#endif
+
+//----------------------------------------------------------------------------------
+// Sets the analog pin, calibration factors for the voltage and phase to be used
+//----------------------------------------------------------------------------------
+void MCMmeter::VoltageStp(unsigned int _analogVin, double _VoltCal, double _PhaseCal)
+{
+  offsetV = ADC_COUNTS >> 1;
+  PhaseCal = _PhaseCal;
+  VoltCal = _VoltCal;
+  analogVin = _analogVin;
+}
+
+//-------------------------------------------------------------------------------------------------
+//  Voltage calculation from a window sample of the analog input from the Grove AC Voltage Sensor
+//-------------------------------------------------------------------------------------------------
+void MCMmeter::analogVoltage(unsigned int cycles, unsigned int timeout)
+{
+
+  cycles = cycles/2; // Converting cycles to zero crossings
+
+  int SupplyVoltage = boardVcc();
+
+  unsigned int crossCount = 0;      // Used to measure number of times threshold is crossed.
+  unsigned int numberOfSamples = 0; // This is now incremented
+
+  //-------------------------------------------------------------------------------------------------------------------------
+  // 1) Waits for the waveform to be close to 'zero' (mid-scale adc) part in sin curve.
+  //-------------------------------------------------------------------------------------------------------------------------
+  unsigned long start = millis(); // timer for the timeout.
+
+  while (1) // wait for the sine signal to zero cross, break if timeout
+  {
+    startV = analogRead(analogVin); // using the voltage waveform
+    if ((startV < (ADC_COUNTS * 0.51)) && (startV > (ADC_COUNTS * 0.49)))
+      break; // check its within range to start from here
+    if ((millis() - start) > timeout)
+      break;
+  }
+
+  //-------------------------------------------------------------------------------------------------------------------------
+  // 2) Voltage measurement loop
+  //-------------------------------------------------------------------------------------------------------------------------
+  start = millis();
+
+  while ((crossCount < cycles) && ((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(analogVin); // Read in raw voltage signal
+
+    //-----------------------------------------------------------------------------
+    // 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) / ADC_COUNTS);
+    filteredV = sampleV - offsetV;
+
+    //-----------------------------------------------------------------------------
+    // C) Root-mean-square method voltage
+    //-----------------------------------------------------------------------------
+    sqV = filteredV * filteredV; // 1) square voltage values
+    sumV += sqV;                 // 2) sum
+
+    //-----------------------------------------------------------------------------
+    // E) Phase calibration
+    //-----------------------------------------------------------------------------
+    phaseShiftedV = lastFilteredV + PhaseCal * (filteredV - lastFilteredV);
+
+    //-----------------------------------------------------------------------------
+    // 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++;
+  }
+
+  //-------------------------------------------------------------------------------------------------------------------------
+  // 3) Post loop calculations
+  //-------------------------------------------------------------------------------------------------------------------------
+  // Calculation of the root of the mean of the voltage and current squared (rms)
+  // Calibration coefficients applied.
+
+  double V_RATIO = VoltCal * ((SupplyVoltage / 1000.0) / (ADC_COUNTS));
+  Vrms = V_RATIO * sqrt(sumV / numberOfSamples);
+
+  // Reset accumulators
+  sumV = 0;
+  //--------------------------------------------------------------------------------------
+}
+
+//-------------------------------------------------------------------------------------------------------------------------
+//  Function that measures the supply voltage of the boards.
+//-------------------------------------------------------------------------------------------------------------------------
+long MCMmeter::boardVcc()
+{
+
+  long result;
+
+#if defined(__AVR_ATmega168__) || defined(__AVR_ATmega328__) || defined(__AVR_ATmega328P__)
+  ADMUX = _BV(REFS0) | _BV(MUX3) | _BV(MUX2) | _BV(MUX1);
+#elif defined(__AVR_ATmega644__) || defined(__AVR_ATmega644P__) || defined(__AVR_ATmega1284__) || defined(__AVR_ATmega1284P__)
+  ADMUX = _BV(REFS0) | _BV(MUX4) | _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
+#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 the reference voltage to stabilize
+  ADCSRA |= _BV(ADSC);                          // Convert
+  while (bit_is_set(ADCSRA, ADSC))
+    ;
+  result = ADCL;
+  result |= ADCH << 8;
+  result = READVCC_CALIBRATION_CONST / result;  // 1100mV*1024 ADC steps
+  return result;
+#elif defined(__arm__)
+  return (3300);                                // Arduino Due
+#else
+  return (3300);                                // Assuming other architectures works with 3.3V!
+#endif
+}

MCMVoltSense.h

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

examples/VoltageSensing/VoltageSensing.ino

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

keywords.txt

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

library.json

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

library.properties

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