acs711 + arduino

arduino-acs711.ino

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 = 1126400L / result; // Back-calculate AVcc in mV 
return result; 
}

const int analogIn = A0;
int mVperAmp = 90; // from datasheet
int RawValue= 0;
double Voltage = 0;
double avgVoltage = 0;
double Amps = 0;

void setup() 
{ 
  Serial.begin(9600);
}

void loop() 
{ 
  Serial.println( readVcc(), DEC );
  RawValue = analogRead(analogIn);
  Voltage = ((RawValue / 1023.0) * readVcc()) / 1000; // Gets you mV
  avgVoltage = Voltage / 1.025; // magic 
  Amps = ((Voltage - (readVcc() / 2)) / mVperAmp);
  Serial.print("A0 = " ); // shows pre-scaled value 
  Serial.print(RawValue); 
  Serial.print("\t V = "); // shows the voltage measured 
  Serial.print(avgVoltage,2); // the '3' after voltage allows you to display 3 digits after decimal point
  Serial.print("\t Amps = "); // shows the voltage measured 
  Serial.println(Amps,2); // the '3' after voltage allows you to display 3 digits after decimal point
  delay(1000);
}