Question

How many RX-TX pairs of pins are present in the Arduino Mega?

(a) 1

(b) 2

(c) 3

(d) 4

This question was addressed to me during an interview.

This interesting question is from Serial and Stream Communications in division Arduino Programming of Arduino

Answer 1

The correct option is (d) 4

The best explanation: The Arduino Mega has 3 RX-TX pairs; 0&1, 19&18, 17&16 and 15&14. The Serial pins are used for establishing and maintaining communications between the computer and the Arduino. However, once any of these RX-TX pairs are setup for serial communications, during the course of the program they cannot be used for GPIO.