I am curious if anyone has a unique or novel method for updating a 
flash-based pic in the field.

A basic requirement is that this update has to survive interruption, 
such as power-off during programming.  So probably, I would have some 
sort of logic level output for a watchdog signal.  I would then try 
programming again if there was a failure.

Also, I am looking for automatic update from a host device, and I am 
currently focusing on a design that would implement 
Single-supply/Low-voltage ICSP on the host.  I do need to research using 
some sort of boot loader, as I am not sure how well the boot loader 
would hold up against power interruption or other failure.

The host will be a custom platform (utilizing FPGAs, actually), and can 
be thought of as a black box.  I have a little bit of freedom so I am 
open to any suggestion you may have.

Unless I am mistaken, JTAG support is also probably not easily 
implemented, correct?

I think ICSP is the way to go, but I want to explore all the options.

Thanks for the help,

-steve

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