Latest Board Design
Below is a picture of what we hope will be the final board design -- the one we'll send to the big fab for our first production run. We ordered a small batch from OSH Park in order to make sure our modifications pass muster.
Hopefully, those of you who are interested in the board as a development platform will be able to see what's being offered here. All 14 of the standard Arduino digital I/O pins are exposed on both chips, plus two analog pins per chip. Each chip's reset pin is exposed. And if you're really savvy, there's one pad to both chips for a pin that doesn't even appear on the DIP-socket version. There are spots for 16MHz ceramic oscillators, which will be important to run the serial connection at high baud rates. The TX/RX lines go through the entire matrix, so you can program any chip to be controller and/or recipient of instructions. You basically have 31 I/O pins per board at your disposal (28 on the edges, plus TX, RX, and RIN), including 5 analog inputs!
Once we've reached our final design, we'll provide the board files. We don't want to release anything with errors.