[sdiy] DIY PG-800?

[Matthew Smith]

Quoth Colin f at 2008-12-24 11:07...
> http://www.colinfraser.com/jx10/moreinfo.htm

Quoth Ullrich Peter at 2008-12-25 00:20...
 > And you can have a look at the Service Manual of the PG-800 that is
 > part of the JX8P Servoice Manual -
 > at least the schematics of the PG-800 are here. It works with an 8048
 > microcontroller that can normally be copied
 > as it had no code protection as far as I know. You should fine someone
 > that has the PG-800 and can copy the 8048 for you...
...
 > maybe some information also in the MKS70 Service Manual:

Thanks guys!

Colin's page provides all the codes bar the one for the 'write' command.

Looking through the PG800 and MKS70 service notes reveals the wiring of 
the connector.

Certainly a copy of the firmware would make it possible to reproduce the 
original circuit. (I'm not sure if uPD7001C ADCs are still manufactured 
but everything else is standard parts, much to my surprise.)  This, 
however, still means that access to a PG800 would be required.

To complete the picture so that the system could be reproduced without 
the firmware I would need to know details of the serial protocol that 
are not documented in the service notes:

* Should data be presented on the rising or falling edge of the clock?
* Is the data 7 or 8 bit?
* What polarity is the data (is the logic inverted?)
* What part does the 'ready out' line play?

...questions that could (possibly) be answered with a PG800 and a scope. 
  (Have scope, not PG800 - back to that again.  Doh!)

Maybe it would just be simpler to use sysex, even if it does mean that 
I'd have to implement MIDI merge :-/

/me goes hunting for MIDI merge algorithms.

Cheers

M



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Matthew Smith
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