Hi Tom, that definitely helps, thanks

I'm pretty sure the processor is soldered in (SMT); firmware updates are via USB, and I'm not sure whether it can transmit or receive MIDI via USB.
There won't be any way to get hold of the source code, either, unfortunately. I'm guessing something like the
Magic Lantern project (reverse-engineered, freely available firmware for Canon cameras) would need to happen, but the likelihood is slim. The programming is beyond my capabilities as well.
I'm glad for the info, though, thanks very much!

Cheers
Pat