When the button is pressed the Arduino board will put pin 2 in HIGH state, meaning 5V on pin 2. This voltage is used to drive the transistor that will switch ON the relay and the load (in our case the ...

Enter the ExtraCore library for Arduino, a software library that turns two or more Arduinos into a multi-core microcontroller with more pins than you’ll ever need.

Not long after [CulinarilySpeaking] got into the Arduino game, he began to want more IO pins and a larger program space for more ambitious projects. This, of course, led him down the path towards t… ...