Cool, thanks man! The design I'm working with only has 48 keys. It's a sorta split design, but all one piece for now... think Kinesis Advantage-ish. Sounds weird but the natural sort of grid would be a 3x8 on each side or I guess a 3x16, although the wiring might get weird with the controller being in the middle between the two halves of the grid.
Sounds pretty cool!
So to make a keyboard matrix for that, you need at minimum 2*(48^0.5) pins, which is 14 (7 by 7 matrix will have 49 possible positions) but if you are hand-wiring this it will be pretty tough.
A lot easier would be to wire it up as two 8*3 matricies, or one 8*6. This would require 8 + 6 = 14 pins, plenty on the teensy for that. You'll have to have 6 or 7 wires across the gap in the middle though. This would be significantly easier to hand wire.
So another option is to wire it up as a 16*3 matrix. You'd only have 3 or 4 wires across the gap in the middle, and it would require 16 + 3 = 19 pins. again enough on the teensy. This would be just about as easy to wire as the above, and might save you some trouble when coming up with a cable for the split halves. This is probably your best option, but it's a lot less efficient than either of the above. (less pins available on the teensy for things like LEDs and stuff)
If it's all in one piece for now either of the last 2 options are about the same, but the last would be easier to make fully split.
In any of these cases a teensy++ is not required.
Let me know if you need any more info. I can draw out a wiring diagram if you need. I'm a visual learner so things like that help me out a lot.
