Just thought I'd share a quick update. I've been making some minor tweaks to the PCBs and sorted out a couple of issues and made some improvements:
1) beefed up the power traces. All the traces on the board the first time round were 10mil, I've sinced uped the 5v & gnd rails to 15mil, including bulking up the vias.
2) added a crystal to both sides of the main & thumb boards. I still have a ways to go w/ pwm control, and the crystals give me the option to bump up to 16mhz if I need to.
3) caught a routing problem on the main board, right side. Missed some I/O >_<
4) added an additional pair of address jumpers. You can now add up to 16 (8 per side) thumb pads.
5) added a 3.5mm connection point to thumb pads for external use.
6) sorted out connectors between main & thumb boards. There are options for permanent & modular connections.
7) shifted over & optimized main boards ISP header. This allows for a pass through connector to be used on the RGB add on, simplifying the connection without using something difficult like ZIF cables.
added inline spi header to CPU module for future bluetooth addon.
9) added indicator LEDs to CPU board for power & USB tx/rx (mostly troubleshooting). Can be disabled via a jumper.
10) designed external number pad.
11) designed external 4x5 button array.
12) updated case designs to accommodate pcb changes. Also moved and added case screws for better stability. I have button head & counter sunk screws on order for testing.
13) outlined the addressing table for all boards.
13) outlined the i2c commands for switch polling & LEDs on the sub boards.