Envelopes and LFO via Aout

[Synthy]

I want to control a CEM3396 chip with MIOS. For this purpose it i have to send the envelopes and LFO output trough Aout. How can i do this? I know it's possible because the Midibox FM and Sid are working this way.

[stryd_one]

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There are a few of us (including myself) who have 3396's and have been planning to make a synth with them, so I'm sure you'll get lots of help... But first you should run a search and catch up with the state of this concept.

[moxi]

maybe it's the good place  :) :

i'm finishing my mods of the "analog_toolbox" application:

it's the same as the original, but with :

- a third lfo

- 3 waveform for the lfos (sine-saw-square) selectable with a dedicated buton by lfo

- 3 leds per LFO to see which waveform is selected

- a buton to modulate the first lfo rate by the second lfo

- a buton to modulate the second lfo rate by the third lfo (so you can modulate the first LFO by the second who is modulated by the third - the result look strange on the scope...I've to finish the cem3378 pcb to see how it work "realy")

- a buton to modulate the second lfo rate by the eg

- one led per buton

all of this work already fine.

to do:

- add some butons to modulate the EG parameter by the LFO

- a preset mechanism to be abble to store 8 config quickly recallable from 8 butons..but this mod is a bit far away from my skillz now..

let me know if you want to test this apps.

the purpose of this is to drive two cem3378 filter, i've build some "cv distributors" and "cv mixers"  that i will place between the Aout module and the cem cv inputs, so each mod source will be mixable for each cv controled parameter of the cem chip... a bit ambitious, so things go slowly... ::)

[Ashiman]

sounds great to me !! what would be great too if you can have these merged, crossmod LFO-s in slots where you can place math formula! Can you post some scope pic ? :)

[TheAncientOne]

what would be great too if you can have these merged, crossmod LFO-s in slots where you can place math formula!

What would be great for this is a DSP chip! Have you any idea of the processor overhead for math formulae?, not to mention the floating point arithmetic needed.

Running real time math formulary is better done by something with some real horsepower. PIC is a wonderful microcontroller, but it's just not equipped.

If you really want math formula LFO's then your best bet is to pre-compile wavetables on a PC, and see if you can squeeze them into a look up table in the pic - downloading them as needed. You couldn't vary the parameters in real time, but you could change frequency and amplitude.

To get a handle on this type of thing, it might be worth having a go at CSound, (if you're an old school programmer), or Chuck.

[Ashiman]

well my utterly limited experience comes from fruity loops where I started to play around with sometihng like this:

adequate for me now ( not to mention the wonderful builtin envelope controller!!)

[TheAncientOne]

Running on a pentium which has ..... guess what? A floating point processor on chip, and is processing at least 20 times as fast as a PIC

Horses for courses.

Like your use of fruity - I bet you got that in a couple of hours, whereas I'd probably have faffed around all night trying to weld something up out of CSound functions and still had no HUI.

[Ashiman]

it was basically lot less cause i only typed the 3.rd ^^

If we resort to floating point then basically we re left with FPGA cause I cant see a Sharc DSP in diy territory anytime soon. I had an idea of doing this inside PC (controlled by midibox^^) and LFO / ENV values transmitted into a 70Usd avr32 devkit thru ethernet, doing nothing else than an oversized FIFO , loading 64bit OSC timestamps and driving the multichannel voltaeg out DAC. Not much interest generated in that topic.

[TheAncientOne]

Yeah - I took a look at the 'low cost evaluation kit' for SHARC. Starts at $400. The Blackfin ones are marginally cheaper, though they do have offers if you can convince them you're a student or you want to use 10K pieces.

Coldfire is not quite in range, but the dev kit is cheaper. If I was planning an upgraded controller I'd be going ARM, lots of devices, (including IP cores for FPGA, and FPGA's with up to 4 ARM's built in), and some reasonable dev tools, including a lot of GPL stuff. A bit more 'future proof'.

AD did have a great card for PC's called 'Sphinx'. It would run a version of CSound in realtime too. Sadly, that seesm to have been absorbed into Creamware somehow, and people who can  afford that stuff  wouldn't be doing much DIY, I guess.

I did a bit with cluster computers, a while ago, (Beowulf and MOSIX), though only on the hardware side, my programming is not in that league. We found the ethernet 'overhead' to be significant, hence those exotic cards built for that type of work. A dedicated high speed serial link migh be better, or perhaps using an FTDI interface module.

A thought anyway.

[Ashiman]

yes I was aware of that dsp csound version back then , it dissapeared somehow LOL. I think the best deal right now is ML402 fpga devkit from ebay, 200-250USD . Virtex4 with hardwired powerpc mcu!