referencing unmapped pins - 2560

I want to reference a few pins that don’t seem to be mapped. How does one go about calling one of these pins?

Which pins?

Probably by Direct Port Access:

DDRJ |= 0x08; // Set pin 3 of port J as an output
PORTJ |= 0x08; // Write HIGH to pin 3 of port J

j3 = !!(PINJ & 0x08); // Read pin 3 of port J

What we need is a pins_arduino.h that brings all the pins out so they can be accessed on schmartboard breakout board or similar, this one I think, 0.5mm pitch and a board type that can be called out to use them.

In fact, I’m gonna need that soon. Waiting on some connectors to arrive, and then I’ll be writing some test code to check out operationality.

Thanks for the quick replies, I will give it a try soon.