This is my first post here! I am builiding a custom Arduino board, and I based my design on the Arduino Mega ADK. The microcontroller used is Atmega2560.
The question is: I've seen there are a few pins from the Atmega2560 which are unused in Arduino (they are not wired to any external pin). I am interested in using these pins as outputs. I've done some research and I've seen things about Port Manipulation, etc. but I can't really figure how to do it.
Do I have to modify the bootloader? Is there a file where pins are defined?