We have still not received our boards yet, but someone else has ordered their own copy, and has reported that there are some bugs in the rev 1.0 version. The most glaring issue is the lack of GND flood fill on the back of the board (the zone is there, but had been reset at some point before ordering). This means that we will have to dead-bug 6 wires between vias on the back to get things working properly. Boo!
A rev 1.1 board is well underway with the following changes (see git for details):
- Actually fill the GND plane this time (gah!)
- Use a crystal + caps instead of a resonator. While I believe that we have selected a resonator that will work with USB, apparently crystals make for more stable USB communications.
- Add more decoupling caps (we now have one 0.1uF for each VCC / AVCC pin, with a 1uF on UVCC).
- Fixed the LED footprint to use some dirt-cheap RGB LEDs from eBay rather than the more expensive Cree LED (same footprint, but different pinout). See http://www.ebay.ca/itm/330833693803?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1439.l2649 for the LEDs which we are now using.