[sdiy] DIY PG-800?

[Matthew Smith]

Quoth Ken Luke at 2008-12-24 08:59...
> Are you set on a hardware solution? If not, there are many different
> MIDI editors that you can set up, provided you are using a PC of some
> sort.
> 
> I just sold my MKS-50 & PG300. I once looked inside the PG300 and even
> something that simple (compared to the PG800) looked like it would be
> a significant engineering effort...

Thanks for your reply, Ken.

I do want a hardware solution - I want physical knobs.  Working with a 
computer all the time and having certain health issues, I'm trying to 
use screen (eye strain)/mouse (carpal tunnel) as little as possible for 
my music.  I also find it easier to relate to and understand something 
that I can touch than an on-screen visualisation.  The computer will 
just be used for recording and as a sysex librarian and sending out 
e-mails when something doesn't work ;-)

Creating a hardware editor based on a microcontroller that uses MIDI 
sysex is actually reasonably trivial - or at least it is since I'm 
already working on a design for a low-cost, minimalist MIDI control 
surface.  You just need to poll the state of some switches and several 
analogue channels (the sliders) and shoot out the data if any of these 
change.  You then build the sysex message and send it out of the UART.

A PG-x00 substitute is probably not much more complex from the hardware 
side (just needs the implementation of a synchronous serial interface 
rather than using a UART for MIDI) but the really tricky bit would 
writing the firmware seeing as how the communication protocol is totally 
undocumented.  It would be possible to reverse-engineer by monitoring 
the signals coming out of the PG-x00 but that would take a) time and b) 
you've guessed it - a PG-x00!

So, what it really comes down to is whether anyone has managed to 
reverse-engineer the protocol (or even get it out of Roland: highly 
unlikely).  If not, it will have to be MIDI because at least this is all 
documented in the MKS-70 owner's manual.

Cheers

M

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Matthew Smith
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