Been searching around but am a bit overwhelmed...
I've been working with the PIC24FJ64A for a little while, gradually making
a custom PCB layout for my project; several incarnations now, keep making
silly mistakes.  Anyway, I started investigating USB bootloaders with the
thought that I might need the ability for user firmware updates in the
future, and discovered that the 24FJ64A has a very closely related
brother, the 24FJ64B!  Main difference being inbuilt USB.

Now I'm a fair ways from getting around to doing any bootloading stuff,
but thought I might try to swap chips now and allow room for USB on my
next PCB design, preferably changing only the location of some tracks and
adding some extra components in unused areas;  I've got a cheapie
laser-cut solder stencil, so would prefer to be able to still use it, at
least until the next _major_ revision.  It's almost pin for pin, I can
rearrange some tracks to other pins where required, but what I'm really
unsure of is which exact physical connections are REQUIRED for using USB
for ONLY re-writing the firmware?

I'm guessing D+ and D- are givens, but what about the likes of VUSB,
pull-ups...?  Has anyone found a good diagram of what is required?

I'd like eventually to be able to upgrade firmware via USB, and also
provide power via the USB port for internal recharging (helpful thread a
few weeks back for that).

A datasheet (pins on page 6):
ww1.microchip.com/downloads/en/DeviceDoc/39881e.pdf

B datasheet (pins on page 6):
ww1.microchip.com/downloads/en/DeviceDoc/39940d.pdf

Thanks for any input
Lee

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