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My VEG Project .....
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State Machine
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PostPosted: Fri Jan 26, 2007 6:24 pm    Post subject: My VEG Project .....
Subject description: An 8 channel versatile envelope generator ....
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Here is a picture of a prototype I have been designing and constructing over the last few weeks. Here is a description of the unit without getting too verbose.

The “Versatile Electronic Percussion Dynamics Processor and Envelope Generator” is a standalone multifunction processor module utilizing a hybrid design technique. In this researcher’s application, it shall integrate as part of a larger MIDI interfaced analog six-voice drum system, built and designed here at the sMs electronic music studio. Due to its modular design, the processor also can be used in many other applications as will be described.

The processor has eight full band audio channels with a voltage-controlled amplifier (VCA) in the path of each channel that can either respond linearly or have a Log response to control voltages .

Other sections include: A high speed microcontroller unit (MCU), eight 12-bit voltage output digital to analog converters (DAC’s), mixing amplifiers, serially controlled text/graphic liquid crystal display, and external trigger processor logic and interrupt generator. The DAC’s will drive each voltage-controlled amplifier independently. The eight DAC’s are contained in a single integrated circuit to greatly simplify the circuit wiring, conserve board space, and keep cost low. A built in MIDI interface will accept trigger commands, mode changes, and wave table data. The combination of VCA circuits and high-resolution amplitude programmability in each of the audio channels create a powerful audio manipulation tool. The processor is a tool that can create interesting cyclic, burst, or single shot volume envelopes of infinite variety. Also, the unit’s ability to accept an audio input and selectively pass portions of this audio in virtually any duration and amplitude in accordance to a programmed envelope shape could be used as a tool that can perform an assortment of granular synthesis techniques. The possibilities are numerous.

The VEG can generate 2048 different waveforms with it's 512KB Flash memory installed. If I use an SD interface, I have an microwire port left over in the microprocessor, I can have giga-bytes worth of waveform data!!

All eight channels can either be 0-5 V, 0-10 V control or +5 to -5V audio outputs and are fully programmable via MIDI commands.

Here are more applications:

MIDI to CV
Sequencing
MIDI Compression
Pulsar Granular Synthesis
Multi LFO
Harmonic Generator (High speed AM of incoming audio)
ADSR Generator
Analog Drum Triggering via MIDI interface (Like UD-1's or any other module that will respond to a trigger pulse.)


The list goes on ......

Thanks for reading ......

Bill


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blue hell
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PostPosted: Fri Jan 26, 2007 6:44 pm    Post subject: Reply with quote  Mark this post and the followings unread

Cool project !

Maybe it could benefit from an ethernet / osc interface ? But when only a micro wire interface is left over for I/O I'd go for the memory card interface as well I guess Very Happy

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also .. could someone please turn down the thermostat a bit.
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toybox



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PostPosted: Fri Jan 26, 2007 8:43 pm    Post subject: Reply with quote  Mark this post and the followings unread

Nice!!! looks like you put allot of work in to it
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State Machine
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PostPosted: Fri Jan 26, 2007 8:57 pm    Post subject: Reply with quote  Mark this post and the followings unread

Quote:
Cool project !

Maybe it could benefit from an ethernet / osc interface ? But when only a micro wire interface is left over for I/O I'd go for the memory card interface as well I guess


Yes, the Microcontroller I am using does not have a USB hardware or Ethernet engine in it which would have made it better (faster) in terms of PC connectivity but the MIDI Sys-Exclusive dumps will do just fine. If I want to transfer wavetables over to the device from a PC based sequencer. and each waveform only consists of 256 bytes plus a small bit of overhead, at 330 uS per byte over the MIDI loop, that would take roughly 90 milliseconds per waveform. If I transfer, say, 8 waveforms to cover all 8 channels of my modulator, it would only take 0.72 seconds using a MIDI SYS-EX transfer. Not bad and not all that crazy overhead that USB or Ethernet requires.

Right now the memory is 512 KB of flash which will hold 2048 256 byte waveforms and will suffice. The secure digital memories have a microwire interface, which my microcontroller has, I can get a 2 GIG SD card and hold 8 million waveforms .. shit, thats too much! I think I will stick to the 512KBmemory for now in this prototype.

Bill
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State Machine
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PostPosted: Fri Jan 26, 2007 9:03 pm    Post subject: Reply with quote  Mark this post and the followings unread

Quote:
Nice!!! looks like you put allot of work in to it


Thanks, yes a fair amount of work went into this. The firmware is a challenge as I can have all 8 channels doing different things. One can be a MIDI to CV while 4 others are generating various continuous waveforms at different frequencies, another can generate a burst of 25 cycles when hit with a trigger, another can be responding to velocity data and outputting a voltage for a VCA, and the last generating ADSR in response to a GATE. You get the picture I am sure .......

Bill
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mono-poly



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PostPosted: Fri Jan 26, 2007 9:38 pm    Post subject: Reply with quote  Mark this post and the followings unread

Shocked woow what a great project!
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The Alison Project



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PostPosted: Sat Jan 27, 2007 6:24 am    Post subject: Reply with quote  Mark this post and the followings unread

Very impressive.

Design and construction over the last few weeks, DAMN.....
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v-un-v
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PostPosted: Sat Jan 27, 2007 9:36 am    Post subject: Reply with quote  Mark this post and the followings unread

Blue Hell wrote:
Cool project !


Very cool! Very Happy

(although my heart always sinks when I see the quality of your wiring Bill Shocked Cool )
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fonik



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PostPosted: Sat Jan 27, 2007 12:38 pm    Post subject: Reply with quote  Mark this post and the followings unread

great work, bill! looks awesome. i plan to do a box with different drum modules so this projects looks like a must...
you call it prototype so may i assume that you plan to release your work to the SDIY community (i.e. offering PCBs, source code/preprogrammed PICs)?

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State Machine
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PostPosted: Sat Jan 27, 2007 4:04 pm    Post subject: Reply with quote  Mark this post and the followings unread

Quote:
great work, bill! looks awesome. i plan to do a box with different drum modules so this projects looks like a must...
you call it prototype so may i assume that you plan to release your work to the SDIY community (i.e. offering PCBs, source code/preprogrammed PICs)?


Yes, this is sort of a work in progress and probably will not be sold commercially so the answer is yes, the work will be made public domain most likely to the SDIY community. There is one CPLD (XC95108)) and 18F8722 MCU that would need to be preprogrammed along with wavetable Flash EEPROM but I would offer those to anyone interested. Some may have the capability to program the parts themselves. I really should make the firmware upgradeable through the MIDI SYS-EX dump standard. the MCU has 128K of flash memory and is self programming. I would just need to invoke a boot loader. The MIDI dump and flash programming would probably take 60 seconds plus the overhead. With a unit like this, the firmware would change from time to time.

I will have the main modulator board as a separate entity (PCB) providing various voltage standards. My VCA designs can hang on a VEG output as easily as say a VCO, LFO, Sample and Hold, VCF, or whatever. It's really a very experimental piece of gear. There will be 8 analog trigger/gates as well as triggers through MIDI. Anyone of those events can trigger an event on a channel. The algorithm thats gets initiated won't care who triggered it. Even if you hung, say, 8 drum modules off the VEG, the MIDI interface can be used to trigger each one in accordance with it's own note number thats assigned to it. Another application would be to trigger 4 drum modules, route their outputs to 4 VCA channels and use 4 channels for velocity control for each drum by routing their outputs to the GAIN CV input of each of the 4 VCA's. This can give the performance some expression.

As you can imagine, when you have a high speed controller driving 8 independent DAC's with 12-Bits of resolution each, there are many possibilities. I just developed some Lin/Log VCA's along with it so I can study some Granular synthesis techniques in hardware. The DAC's would created the grain envelopes for VCA modulation either from an external signal source or from a waveform generated by another channel from the VEG.

Bill
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fonik



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PostPosted: Sun Jan 28, 2007 6:30 am    Post subject: Reply with quote  Mark this post and the followings unread

did you ever work with PICs? i plan to buy myself a PIC programmer (want to build some MIDI2CV converters from m. bareille).

i wonder what i could do else with PICs: VCOs, VCFs, LFOs? what skills would be recommended? i never wrote source code before, so i wonder if i could ever achieve it? any ideas, comments?

there're some SDIYers working with FPGAs - which i think is way to sophisticated for me..

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blue hell
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PostPosted: Sun Jan 28, 2007 7:10 am    Post subject: Reply with quote  Mark this post and the followings unread

fonik wrote:
any ideas, comments?


Maybe look at sites like : http://www.piclist.com/techref/piclist/index.htm and be sure to have a look at http://www.microchip.com - not to let the enourmous amount of availble PIC's confuse you, it might be best to look around a bit at other sites first to see what PIC's are used ifor projects that you like, then go the microchip site to download the tools and the data sheets. I'd recommend to program 'm in assembly language, that way you're closer to the real thing.

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also .. could someone please turn down the thermostat a bit.
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23isgood



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PostPosted: Sun Jan 28, 2007 12:15 pm    Post subject: Reply with quote  Mark this post and the followings unread

Here you go. Pic LFO, and EG,

http://www.tomwiltshire.co.uk/sdiy/

I actually have two programed pic's from Tom that I need to build into an LFO and ADSR.

pete
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fonik



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PostPosted: Sun Jan 28, 2007 12:36 pm    Post subject: Reply with quote  Mark this post and the followings unread

23isgood wrote:
Here you go. Pic LFO, and EG,
http://www.tomwiltshire.co.uk/sdiy/
I actually have two programed pic's from Tom that I need to build into an LFO and ADSR.
pete

oh yeah, there was a note 'bout this in the SDIY list but i didn't follow that thread! i missed it. thank you very much for that reminder!
a friend of mine is a professional chief programmer, i will talk to him about all that soon...

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Scott Stites
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PostPosted: Fri Feb 02, 2007 10:27 pm    Post subject: Reply with quote  Mark this post and the followings unread

Playing catch-up - quite splendid, Bill! Looks exciting.

Cheerios,
Scott
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State Machine
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PostPosted: Sun Feb 04, 2007 11:36 am    Post subject: Reply with quote  Mark this post and the followings unread

Quote:
Playing catch-up - quite splendid, Bill! Looks exciting.


Yes, thanks. I am sitting here doing some firmware for it as I write this. I have the in circuit serial programmer hooked up so I can make a code change, assemble and flash the code in seconds and see the change in hardware immediately on my scopes. I am using a HP54645D Mixed Signal Oscilloscope for this job with 2 analog and 16 digital channels.

OK, gotta get back to it ........ chat later !

Bill
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