AC meter By ADC timer interrupt from Nick Gammon I want to read ADC from the pin A0 and A1. I have written in this code, however.

I took this code came from Nick Gammon  

Thank You
//////////////////////////////////////////////////////////////////////////////

this is code

const byte adcPin = 0;  // A0

const int MAX_RESULTS = 256;

volatile int results [MAX_RESULTS];
volatile int resultNumber;

// ADC complete ISR
ISR (ADC_vect)
  {
  if (resultNumber &gt;= MAX_RESULTS)
    ADCSRA = 0;  // turn off ADC
  else
    results [resultNumber++] = ADC;
  }  // end of ADC_vect

EMPTY_INTERRUPT (TIMER1_COMPB_vect);

void setup ()
  {
  Serial.begin (115200);
  Serial.println ();

  // reset Timer 1
  TCCR1A = 0;
  TCCR1B = 0;
  TCNT1 = 0;
  TCCR1B = bit (CS11) | bit (WGM12);  // CTC, prescaler of 8
  TIMSK1 = bit (OCIE1B);  // WTF?
  OCR1A = 39;    
  OCR1B = 39;   // 20 uS - sampling frequency 50 kHz

  ADCSRA =  bit (ADEN) | bit (ADIE) | bit (ADIF);   // turn ADC on, want interrupt on completion
  ADCSRA |= bit (ADPS2);  // Prescaler of 16
  ADMUX = bit (REFS0) | (adcPin &amp; 7);
  ADCSRB = bit (ADTS0) | bit (ADTS2);  // Timer/Counter1 Compare Match B
  ADCSRA |= bit (ADATE);   // turn on automatic triggering

  // wait for buffer to fill
  while (resultNumber &lt; MAX_RESULTS)
    { }

  for (int i = 0; i &lt; MAX_RESULTS; i++)
    Serial.println (results [i]);

  }  // end of setup

void loop () { }
You can read two analog channels like this:

int first_reading = analogRead(A0);
int second_reading = analogRead(A1);


If this does not fit your purpose, then your question was not asked
properly: rewrite it and clearly state your requirements. Explain why
the simple solution does not work for you.

If this does work for you, then stop (for now) reading advanced
tutorials, like the one where you found your code, and focus on the very
basics: the Arduino examples in the 01.Basics section, then the
03.Analog section.