int adc_val;
uint8_t low, high;
unsigned char ti, tc;

void setup() {
  DDRA= 0x00;
  ADCSRA= 0x87;
  ADCSRB= 0x00;
  ADMUX= 0x40;
  Serial.begin(9600);
}

void loop() {
  ti= micros();
  ADCSRA |= (1<<ADSC);
  while((ADCSRA & (1<<ADIF))==0);
  low= ADCL;
  high= ADCH;
  adc_val= (high<<8)|low;
  tc= micros()-ti;
  Serial.print("ADC Value= ");
  Serial.print(adc_val);
  Serial.print("Conversion time= ");
  Serial.print(tc);
}