[Thumbgps-devel] PPS over USB Serial can work

[tz]

http://www.sparkfun.com/products/10277

It doesn't support CTS/DCD/RI "out of the box", but the source is
there.  We can name it what we want (there is the vendor/product ID
problem - we should be able to get one, but the text string can be
uniquely ours).

The base code (at github) has a delay to buffer characters with a
timeout, but that can be eliminated or short circuited for the "$"
which begins NMEA sentences.

I haven't seen all the LUFA library, but going from the ICP interrupt
to sending a DCD shouldn't be that hard.

more here - I haven't found DCD support yet but it shouldn't be hard to add.