Question

What is the function of the AREF pin in the Arduino UNO?

(a) It is used as a reference voltage for all analog voltage calculations in the board

(b) It is used as a reference voltage for all digital voltage calculations in the board

(c) It is used as a reference voltage for the power source on the board

(d) It is used as a reference voltage for the ground pins on the board

This question was posed to me in an interview for internship.

My doubt stems from Board Pinout Structure in division Board Specifications and Types of Arduino

Answer 1

Right answer is (a) It is used as a reference voltage for all analog voltage calculations in the board

For explanation: The AREF pin is used internally by the board for measuring the analog voltages. By default, if nothing is connected to it then it will give the range for analog voltage calculation as 0-5V. But this pin when connected to a lower voltage say 3V will set the range for voltage calculations from0-3V.