Very nice arduino implementation.
I’m very interested in the 3V mode. How did you get that to work? I only see 1 voltage regulator on the board. What about the clock frequency- is still 16Mhz for both 5V and 3V? Will it work with both USB and EXT power?
Also, it’s hard to tell from the picture, but is there actually room for both sets of headers on the digital pins? Or do you have to pick one or the other?
Thanks,