sanni:
That should be quite easy to integrate since there is already an Atmega2560 port available in the pull requests of the Github you linked.
Basically you just have to replace all the serial stuff with the SD stuff.
You can look at the SMS.ino file in the Cart_Reader folder to see what exactly is needed to add a new system to the Cart Reader project as the SMS.ino is the smallest file so far.It could also be that Sketchup did an error when exporting, you can run the STL file through Meshmixer or Windows 10 3D Builder to automatically fix errors.
I'd love to get this working unfortunately I have no idea where to begin. I suppose it's a matter of looking over the SMS.ino and basically copy/paste sort of thing. I'll attempt it as soon as I can get a chance. Hopefully this weekend.
Running the file through Meshmixer seems to be the same sort of thing.I don't know what's going on.
And I wanted to share this list of different SNES game chips as a reference for others.
[EDIT]
I began working on the diagram earlier
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Here is what I got so far but the 7.6v threw me off, the 3.6v and 5v I wondered about the switch already on the board operating this. I began looking over the code as suggested but quickly got lost with how to go about it. The last coding I did was in Java and it's been about two years.
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Here is a comparison if someone could even begin to walk me through it so I can get an understanding of things it would be appreciated.