Sat Aug 17 18:47:27 EDT 2013

Debug console over USB

It might be better to work in an event-driven way instead of the
blocking console approach of before.  It might also be useful to
standardize the console such that different systems could use it,
i.e. not just Staapl.

The first thing to get going is the debug console over USB control
requests, i.e. working packet based and giving up on serial line

The first thing that's necessary is a debug ringbuffer.  It seems
quite clear now that debug messages that delay execution are not
useful for debugging real-time systems.  This could be just a linux
usbserial port.

How many end points are there in the PIC?  Up to 32, so that's not a
problem.  Let's start there.  Buffer could be emptied at each SOF.

Because of non-blocking request, a double buffering approach would be
necessary.  Best to get that going first.

Ok, so that was easy!

Didn't need to change anything in the protocol, just using the sync
words to flush the comm at the end of a command.