Reading analog signal from digital pin #6

Question

Is it possible to use digital pin 6 (PD6_PCINT22/AIN0) to read an analog voltage with analogRead()?

According to the ATMega datasheet, this should be possible.

If yes how is it done ? (pin configuration)

Answer 1

That is not possible. AIN0 is an input to the analog comparator, not the analog-to-digital converter. Only ADC0 through ADC8 (connected to the internal temperature sensor), the 1.1V reference, and ground can be connected to the ADC.

Answer 2

Maybe. The Arduino board contains a 6 channel (8 channels on the Mini and Nano, 16 on the Mega) and the number of the analog input pin to read from (0 to 5 on most boards, 0 to 7 on the Mini and Nano, 0 to 15 on the Mega).

As you can see in the image below the pin PD6 is not an analog input. To be an analog pin it should be write ADCx, like the PC0..5.

enter image description here

So, if you are not using and Arduino Uno you can't use PD6 as analog input but you can use PC0..5.

To read an analog value using analogRead() method you can do like this:

int analogPin = 3; 
int val = 0; // variable to store the value read
void setup()
{
 Serial.begin(9600); // setup serial
}
void loop()
{
 val = analogRead(analogPin); // read the input pin
 Serial.println(val); // debug value
}