How do the analog pins found on the 20-pin header (pins A0, A1, A2, etc.) differ in function and purpose from the auxiliary analog pins (AA0, AA1, etc.)? From what I’ve seen, you need to connect analog sensors to the auxiliary analog pins and use an Adafruit library to get the millivolt readings because of an ADC they are connected to. I’ve successfully done this, and it has worked great, but I guess I’m curious what the other analog pins (A0, A1, etc.) on the 20-pin header are used for and what type of sensor outputs would be used on them.