The ExtraCore library comes from [Dustin Andrews], and allows anyone to control the input and output pins of two Arduinos with the same ease as a single Arduino. The hardware setup is fairly ...

The Uno also has a limited number of pins, making it difficult to work with when the project requires plenty of input and output components. However, these two areas are where the Arduino Mega shines.

There are five input pins to the chip ... That is, it isn’t really connecting one output to 32 inputs. It is more like a 32-position switch that connects a single pin out of 32 to one other ...