ACS712-30A Medições com Carga

// Medições de tensão Vout com carga -  sensor ACS712-30A com Arduino ATmega328 - Gustavo Murta 01/ago/2015
// http://provideyourown.com/2012/secret-arduino-voltmeter-measure-battery-voltage/
// https://code.google.com/p/tinkerit/wiki/SecretVoltmeter
// https://github.com/openenergymonitor/EmonLib

    //--------------------------------------------------------------------------------------
    // Variable declaration for emon_calc procedure
    //--------------------------------------------------------------------------------------
    int sampleV;                 //sample_ holds the raw analog read value
    //int sampleI;

    double lastFilteredV,filteredV;          //Filtered_ is the raw analog value minus the DC offset
    // double filteredI;
    double offsetV;                          //Low-pass filter output
    // double offsetI;                       //Low-pass filter output

    double phaseShiftedV;                    //Holds the calibrated phase shifted voltage.

    double 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.

long readVcc() {
  // Leitura da tensão de Referencia de 1.1V para calcular  AVcc
  // Configura Referencia do ADC para Vcc

    ADMUX = _BV(REFS0) | _BV(MUX3) | _BV(MUX2) | _BV(MUX1);

  delay(2);                         // Aguarda estabilização da Tensão Vref
  ADCSRA |= _BV(ADSC);              // Inicia a conversão ADC
  while (bit_is_set(ADCSRA,ADSC));  // Começa a leitura

  uint8_t low  = ADCL;              // Lê primeiro o registrador ADCL e depois o ADCH
  uint8_t high = ADCH;              // destrava os dois registradores

  long result = (high<<8) | low;    // Formata o resultado

  // Conversor ADC do Arduino já calibrado
  // Primeiro ReadVcc = 1.1 * 1023 * 1000 > Vcc = 4957 mV
  // Com Multimetro Vcc = 5000 mV e Vref = 2500 mV
  // Com Arduino    Vcc = 5000 mV e Vout = 2497 mV

  result = 1135061L / result;        // Cálculo do Vcc (em mV) 1135061 = 1.109542*1023*1000
  return result;                     // Vcc em millivolts
  }

  unsigned int crossCount = 0;       // Usado para determinar a quantidade de passagens por zero
  unsigned int numberOfSamples = 0;  // Quantidade de amostragens
  unsigned int crossings = 20;       // quantidade de semiciclos da senoide
  int timeout = 2000 ;
  define ADC_BITS    10
  define ADC_COUNTS  (1<<ADC_BITS)

  //-------------------------------------------------------------------------------------------------------------------------
  // 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(A2);        //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++;                       // Incrementa o número de amostragens
    //lastFilteredV = filteredV;             // Used for delay/phase compensation

    //-----------------------------------------------------------------------------
    // A) Medições de Tensões  no pino A2 do Conversor ADC
    //-----------------------------------------------------------------------------
    sampleV = analogRead(A2);                 //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)/1024);
    filteredV = sampleV - offsetV;

    //-----------------------------------------------------------------------------
    // C) Root-mean-square method voltage
    //-----------------------------------------------------------------------------
    sqV= filteredV * filteredV;                 //1) square voltage values
    sumV += sqV;                                //2) sum

    //-----------------------------------------------------------------------------
    // D) Phase calibration
    //-----------------------------------------------------------------------------
    //phaseShiftedV = lastFilteredV + PHASECAL * (filteredV - lastFilteredV);

    //-----------------------------------------------------------------------------
    // E) Instantaneous power calc
    //-----------------------------------------------------------------------------
    //instP = phaseShiftedV * filteredI;          //Instantaneous Power
    //sumP +=instP;                               //Sum

    //-----------------------------------------------------------------------------
    // F) 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 = 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;
 //--------------------------------------------------------------------------------------
}

 void setup() {
  Serial.begin(9600);
}
void loop() {
  long Vcc = (readVcc());
  Serial.print("Vcc = " );
  Serial.print(Vcc);
  Serial.println(" mV" );

  int Vin = analogRead(A2)+1 ;        // leitura da tensão no pino A2 + LSB
  long Vout = (Vin * Vcc) / 1023;
  Serial.print("Vout = " );
  Serial.print( Vout );              // Vout do sensor ACS712-30A
  Serial.println(" mV" );
  Serial.println ();

  Serial.print('Vrms = ');
  Serial.print(Vrms);
  Serial.println(' mV ');

  delay(1000);
}