bootloader that xfers code from I2C into program memory

[picster]

I think you mean YOUR work!

Without posting a VB "updater" (which is going to be very application specific for this case), there's really not much to post.

The idea here is to create a "firmware update file" from a master, so it can be distributed in the field or wherever.

Suffice to say that if your main program has a hidden "dump all my code out via serial" subroutine, then you don't have to muck about with interpreting intel hex files, you just get raw code (instructions) from memory location A to memory location B from your "master" that you've updated with your PIC programmer (the upper memory program is always included with this).

Once you have that "master" file captured by a PC, you can send it back out its serial port to be intercepted by the "main program" on any unit to be UPDATED, and stored on I2C. After checking the checksum, then you call the "reprogram" code sitting in upper memory to rewrite all the lower code, stopping shy of the "tucked" upper subroutine location. Encryption is just a matter of manipulation at the PC end after receiving the original dump, and reverse-manipulation at the PIC end as you pull the words back out of I2C (before doing the codewrite).