I recently spent a bit of time drawing up a proper schematic for MENTAL-1. I've had revised schematics laying around on sheets of paper for a while, but nothing official. However, I wanted to make a PCB implementation of MENTAL-1, so I fired up Altium and drew it up. You can find the hi-res schematic PDF here.
For now, I'll be referring to this implementation as MENTAL-1P. It's a slightly modified design from MENTAL-1, but I'm not sure if it warrants a version number bump. I'll be posting updates here when I get and test the boards from Seeed.