Arduino - Voltage and Current Measurement ACS712, ADS1015

How to make a circuit for voltage and current measurement using Arduino and ACS712, ADS1015. The ADS1015 is a 12-bit analog-to-digital converter. Equipped with i2c bus and 4 channels A0-4. What is very important is also have "Internal Low-Drift Voltage Reference", which significantly simplifies the construction of precision measuring systems. ACS712 is the circuit for measuring the current using a hall effect. My version measures current from -30A to 30A.

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Arduino - voltage and current measurement ACS712, ADS1015

• Arduino Nano
• ACS712
• ADS1015
• Some wires

For testing I used a bulb in the diagram shown as R9. I used resistors R7 and R8 to make the voltage divider.

The following piece of code is responsible for the measurement at the 4 inputs of the ADC. The value "NUMBR_OF_SAMPLES" specifies the number of samples, in this case it is 20. After sampling, the average value of the measurements is calculated.

  int16_t adc0, adc1, adc2, adc3;

  float avg0 = 0.0f;
  float avg1 = 0.0f;
  float avg2 = 0.0f;
  float avg3 = 0.0f;
  for(int i=0; i<NUMBR_OF_SAMPLES; i++){
    adc0 = ads.readADC_SingleEnded(0);
    adc1 = ads.readADC_SingleEnded(1);
    adc2 = ads.readADC_SingleEnded(2);
    adc3 = ads.readADC_SingleEnded(3);

    avg0 += adc0;
    avg1 += adc1;
    avg2 += adc2;
    avg3 += adc3;
    delay( 10 );
  }
  avg0 = avg0/(float)(NUMBR_OF_SAMPLES);
  avg1 = avg1/(float)(NUMBR_OF_SAMPLES);
  avg2 = avg2/(float)(NUMBR_OF_SAMPLES);
  avg3 = avg3/(float)(NUMBR_OF_SAMPLES);

  float voltage0 = DIVISOR0 * (avg0 * 3.0f/1000.0f);
  float voltage1 = DIVISOR1 * (avg1 * 3.0f/1000.0f);
  float voltage2 = DIVISOR2 * (avg2 * 3.0f/1000.0f);

  float w = ( voltage2/5.0f ) * 0.066f;
  float i_cur = ((voltage2 / 2.0f) - voltage1) / w;

  float power = voltage0 * i_cur;

The difference in measurement between DT-832 DIGITAL MULTIMETER and Arduino is very small.