Jesse Lackey wrote:
> The USB firmware stack is a concern

You can try mine, described at http://www.embedinc.com/pic/usb.htm.  We hav=
e
used this code in a bunch of projects by now, including our own USBPprog,
USBProg2, and LProg PIC programmers.  It uses the hardware in ping-pong
buffer mode with triple software buffers per endpoint and direction.  That
means two buffers are queued up ready for the hardware and the third is
available for the software to drain or fill.

I just noticed that web page is pretty old.  Since then we've come out with
the ReadyBoard-02 (http://www.embedinc.com/products/ready02), which is grea=
t
for testing PIC USB concepts or one-off devices.  There is also now a
version of the USB code that uses our multi-tasking system with the
background USB stuff handled in a separate task.  That's usually a cleaner
and easier to write firmware structure for doing I/O than a main event loop
structure.


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