Hello, we have a setup made with a PCB connecting 2 Raspberry Pi 2's to each other via GPIO ports. We connected the GPIO pins without a resistor in between, so a PCB route directly connects them to each other. I saw that a lot of messages advice to use a resistor in between to protect the pins in case both of them are accidentally setup as output pins.
Since our setup is already done using a PCB it is hard and costly to change. I wanted to ask what would happen if I accidentally setup both pins as output? Would the pins burn? Or is there some kind of internal safety resistor of some kind that would prevent something like that?