[sdiy] Data transfer?

The Proteus proteus at ugwarehouse.org
Thu Aug 15 09:01:52 CEST 2002

	Well, I don't want to get bogged down into a lot of file format
stuff - that's what's making any type of downloadability or
programmability such a deterrant to me, but to have this nice dual
oscillator sitting in front of me (as a user), with up to 256 wave
segments and programmable crossfade between each segment and no way to
customize and store my own presets (yes, the evil word) just gets me.
	It seems that this could be split into two separate lines of

1. How does one design a successful, simple, modular-style (buttons and
   knobs) user interface for such a complicated beast?

2. Is it desirable, and if so, what medium would be appropriate for preset
   interchange in the box.

To whet people's appetites, here's roughly what I've got planned:

- Dual Wavetable VCO that will support from 1 to 256 waveforms in 
  a single sequence.
- Fits in a SynthTech 2U or 3U module (pending Paul's permission... I 
  haven't asked yet if it's okay to defile his analog domain with digital
  interpolation!) :-)
- Standard Gate / Trigger / CV in for note on and ADSR, as well as Linear
  FM input, Wavetable sweep, and Wavetable trigger
- Unit can be configured as either a Dual mono or single stereo VCO, with
  CV in for pan control in mono mode.

Beyond that, I've got a laundry list three pages
long. :-) Architecturally, there will be a pretty simple CPU controlling a
custom interpolator chip I'm designing which has a large amount of SDRAM
hanging off of it. The CPU will also be responsible for converting the CV
and gate signals and interfacing to the front panel. If I'm really
interested in taking the time to do so, and the CPU I pick has an onboard
UART I just might squeeze in a MIDI to CV converter as well.

See below for replies.

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On Wed, 14 Aug 2002, Byron G. Jacquot wrote:

> You might want a CV input for the wave crossfade...then a sequence of
> crossfades could come from MIDI-CV, or any other modules.  I'd like to be
> able to tweak it with an ADSR, at the very least.

Already on the list. What good is a modular wavetable oscillator when you
can't tweak wavetable crossings?

> Smartmedia is relatively easy to implement with a microcontroller...at least
> to some degree.  The problem is that it want's to be written with a DOS
> FAT-12 file system.  All of the desktop interfaces will probably prevent you
> from doing direct block-level reads/writes.

Yeah... this is the crux of doing anything such as CompactFlash,
SmartMedia, and the like. The biggest problem for me is writing the host
PC application if you want to transfer wave sequences between the modular
and PC, or if you want to design a patch on the PC. Best bet for me would
be to do a SoundDiver adaptation. :-) I have been naively toying with the
idea of using a Cypress Semiconductor 8051 based USB controller, then hook
the thing up via USB, but once again the host application is the
hinderance here... I don't want to spend 4 months writing a damn Windows
and MacOS app to talk to an oscillator. 

> There are some small 8-pin DIP EEPROMS that use a 3-wire interface.  You
> could make data cartridges around them, then build a small burning station,
> maybe RS232 to 3-wire...something akin to an EPROM burner or the old
> Oberheim Prommer.  Or is that too close to a Synergy?

Cool idea, but once again the host interface issue is blocked by writing a
host app. Maybe it would be best to just have MIDI->CV on this box and do
controller and sysex to it. Hrm. 

Regards and thanks,


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