Max471 Voltage/Current Sensor

max471.ino

/*
MAX471
*/

long milisec = millis();  // calculate time in milliseconds
long time = milisec/1000; // convert milliseconds to seconds

const int max471VT = A0;
const int max471AT = A1;

unsigned int RawVT= 0;
unsigned int RawAT= 0;

float Voltage = 0;
float Current = 0;
float Vcc;
float Power = 0;
float Energy = 0;
float SumCurrent = 0; 
float AvgCurrent = 0;
float CurrentHour = 0;

long readVcc() {
  long result;
  // Read 1.1V reference against AVcc
  ADMUX = _BV(REFS0) | _BV(MUX3) | _BV(MUX2) | _BV(MUX1);
  delay(2); // Wait for Vref to settle
  ADCSRA |= _BV(ADSC); // Convert
  while (bit_is_set(ADCSRA,ADSC));
  result = ADCL;
  result |= ADCH<<8;
  result = 1125300L / result; // Back-calculate AVcc in mV
  return result;
}

void setup(){  
    pinMode(max471VT, INPUT);
    pinMode(max471AT, INPUT);
    Serial.begin(115200);
}

void loop(){

    RawVT = analogRead(max471VT);
    RawAT = analogRead(max471AT);

    Vcc = readVcc() / 1000.0;
    
    Voltage = (RawVT / 1023) * Vcc;    // scale the ADC
    Current = (RawAT / 1023) * Vcc;    // scale the ADC  
    Power = Voltage * Current;         // Ohm's Law
    Energy = (Power * time) / 3600;    // Watt-sec is again convert to Watt-Hr by dividing 1hr (3600sec)
    // Energy = (Power * time) / (1000*3600); for reading in kWh
    
    SumCurrent += Current;                    // calculate total current
    AvgCurrent = SumCurrent / time;           // average current
    CurrentHour = (AvgCurrent * time) / 3600; // Ah

    Serial.print("Voltage = ");       // shows the voltage measured     
    Serial.print(Voltage,3);          // 3 digits after decimal point
    Serial.println(" V");             // 3 digits after decimal point  
  
    Serial.print("Current = ");       // shows the voltage measured     
    Serial.print(Current,3);          // 3 digits after decimal point
    Serial.println(" A");             // 3 digits after decimal point  
 
    Serial.print("Power = ");       // shows the voltage measured     
    Serial.print(Power,3);          // 3 digits after decimal point
    Serial.println(" W");             // 3 digits after decimal point  
  
    Serial.print("Energy = ");       // shows the voltage measured     
    Serial.print(Energy,3);          // 3 digits after decimal point
    Serial.println(" Wh");             // 3 digits after decimal point  
  
    delay(1500);  
}