How to use adc_in0

Hi everyone,

There’s no documentation on how to use the adc_in0 pin.
I guess it’s pin 0, so I did:

echo 0 >/sys/class/gpio/export
cd /sys/class/gpio/gpio0/
cat value

The value is either 0 or 1, quite random, and will change between reads. There should be 0 voltage on it.
If I poll it fast enough, it just gets more random.

How do I correctly read this pin? I know it should be a value between 0 and 4095, but I’m only getting random 0s and 1s.

thanks