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zthee
Joined: Feb 20, 2008 Posts: 414 Location: Stockholm
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Posted: Mon Jul 07, 2008 3:17 am Post subject:
Wavetable? Subject description: A few questions... |
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I've just finished a wavetable module after the schematics on the CGS site. As you can see I've breadboarded it.. It all works! ..sort of..
Above is the output of the module. I think this should be a sine-wave. Apparently it isn't.
The CGS page for reference.
My first thought was that it's a problem with the counters. But I've checked all the connections twice, and they all go to the correct place (except pin 10 on the 4024 - that's a N.C. and should be pin 9 instead..)
So the counters seems to work fine.
I had my friend burn me 2 eproms (One 2716 and one 2732) - and both gives the same result.
The output form the eprom to the DAC looks like this:
(It's pin 9 of the 2716, but generaly all the output pins look the same).
It's a pulse wave - I've only zoomed in on the bottom part, to show the small irregularities - thinking that they might generate a problem? It should be a normal squarewave?
To me - it feels like it's either the DAC or the eprom?
What kind of output should I be seeing from pin 4 and 2 of the DAC?
And is there anyone that has a working eprom to spare?
Thanks! |
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andrewF
Joined: Dec 29, 2006 Posts: 1176 Location: australia
Audio files: 4
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Posted: Mon Jul 07, 2008 6:59 am Post subject:
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The wavetable needs a high freq wave on the input, I usually plug in a tri or saw from a vco, and crank it up - much much higher than you would normally set your vco.
Some VCOs can't go high enough (Paia for example).
Where did you get the ROM data?
Some of Ken's chips contain unusual waveforms, so don't expect to see sine or tri waves. |
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zthee
Joined: Feb 20, 2008 Posts: 414 Location: Stockholm
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Posted: Mon Jul 07, 2008 7:03 am Post subject:
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I've used a TH XR2206 as the controling VCO.
I got the .BIN from here -> http://home.freeuk.net/lowpass/VCDO.html
Here's some picture of the waveformes:
Edit: Did the CGS wavetable module have it's own .bin file? I just assumed it was the same as the VCDO.. |
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fluxmonkey
Joined: Jun 24, 2005 Posts: 708 Location: cleve
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Posted: Mon Jul 07, 2008 6:43 pm Post subject:
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well, there's yr problem... thats not an audio waveform... it's a space invader graphic file... _________________ www.fluxmonkey.com |
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zthee
Joined: Feb 20, 2008 Posts: 414 Location: Stockholm
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Posted: Tue Jul 08, 2008 12:00 am Post subject:
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Damn it! I knew I've seen those guys before! Haha
So your advice is to burn a new eprom? |
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Ilanode
Joined: Sep 14, 2007 Posts: 80 Location: Berlin/FRG
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Posted: Tue Jul 08, 2008 1:12 am Post subject:
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zthee wrote: | So your advice is to burn a new eprom? |
You might use your's as CV-source for unsual LFO-waveforms. A slew limiter could be usefull here. |
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zthee
Joined: Feb 20, 2008 Posts: 414 Location: Stockholm
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Posted: Tue Jul 08, 2008 3:41 am Post subject:
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Yeah, I thought about that.
And even though it's not the correct waveforms it still sounds kinda nice..
I built the display-driver aswell. But it's not working at all. Or; it displays 1 and refuse to change. I'm running it on +15V - but that shouldn't be a problem?
This circuit is driving me mad! And it's the last of the 23 modules I've built for my modular.. Almost complete and then this comes along. |
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Ilanode
Joined: Sep 14, 2007 Posts: 80 Location: Berlin/FRG
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Posted: Tue Jul 08, 2008 4:51 am Post subject:
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The display probably runs on 5V!? |
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andrewF
Joined: Dec 29, 2006 Posts: 1176 Location: australia
Audio files: 4
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Posted: Tue Jul 08, 2008 8:43 am Post subject:
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Quote: | Did the CGS wavetable module have it's own .bin file? I just assumed it was the same as the VCDO.. |
There were a few different versions - at least, putting out different waveforms and for different chips - 64, 128, etc.
I cannot comment whether they are compatible with the digisound version, best check with Ken.
yep - the display adapter needs 5V, also it is quite tricky wiring up the led display, many different varieties - some are common cathode, some common anode, some don't have common anything! The first two I built never worked properly until this was worked out. |
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otherunicorn
Joined: May 11, 2008 Posts: 136 Location: Australia
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Posted: Tue Jul 08, 2008 6:27 pm Post subject:
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The VCDO ROM is compatible with my circuit. What's going on with your circuit however, is anyone's guess! _________________ http://www.cgs.synth.net/ |
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zthee
Joined: Feb 20, 2008 Posts: 414 Location: Stockholm
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Posted: Wed Jul 09, 2008 1:46 am Post subject:
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Ah, that's to bad, I was hopping that the ROM would be the magic solution to it all
I'll keep guessing and hopefully I'll solve it in the end.
Thanks! |
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otherunicorn
Joined: May 11, 2008 Posts: 136 Location: Australia
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Posted: Wed Jul 09, 2008 2:26 am Post subject:
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Check your address and data lines. more than likely, something is out of order. _________________ http://www.cgs.synth.net/ |
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zthee
Joined: Feb 20, 2008 Posts: 414 Location: Stockholm
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Posted: Fri Jul 18, 2008 2:46 pm Post subject:
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I got the displaydriver up and going by running it on 5V - so now it works!
Let's celebrate with some pictures!
Haven't figured out the problem with the ROM though.. Hope to solve it within the next month or so. I've checked, rechecked and double checked the adress & data lines and all is going to where it should be acording to the schematics. But I think that if I check it like 12 more times I'm gonna find the error!
Thanks for helping out! |
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CJ Miller
Joined: Jan 07, 2007 Posts: 368 Location: 127.0.0.1
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Posted: Wed Jul 30, 2008 3:52 am Post subject:
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You must have gotten a few lines scrambled somewhere. Looking at your scope shots, I can see the waveforms, but they are not reading back in sequence somehow. Your circuit basically works, more or less.
Possibilities? The ROM could have been burned weird. Did you make the burner yourself? Or did you use an EPROM with a slightly different pinout? Are unused logic inputs grounded? Solder bridge or mismatched wire on one or more data or address lines?
Good idea using the XR2206 as a wavetable VCO, I have drawn up some plans a few months ago for something similar. My digital projects have kept getting sidetracked. Good luck! |
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dar303
Joined: Jul 15, 2007 Posts: 97 Location: Sweden
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Posted: Sun Aug 03, 2008 1:34 pm Post subject:
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I burned the eprom for zthee using a sunshine pro burner. I have made several other wavetable roms for myself before but not using this data. I'll try to put one of his roms in my oscillator, even though I have bigger waves I shoud see waveforms and be able to read the data. |
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zthee
Joined: Feb 20, 2008 Posts: 414 Location: Stockholm
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Posted: Sun Aug 03, 2008 1:55 pm Post subject:
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Would be great if we could arrange that sometime in the future!
I've used it even though the output is strange. The digital noise is kinda fun to filter and modulate with |
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etaoin
Joined: Jun 30, 2005 Posts: 761 Location: Utrecht, NL
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Posted: Fri Aug 08, 2008 2:49 pm Post subject:
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Didn't know you still wanted to see the scope pics...
I'll pull out my working CGS wavetable this weekend and make some pics. I had one of the last (or the last) set of boards from Ken. _________________ http://www.casia.org/modular/ |
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zthee
Joined: Feb 20, 2008 Posts: 414 Location: Stockholm
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Posted: Fri Aug 08, 2008 3:09 pm Post subject:
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Etaoin wrote: | Didn't know you still wanted to see the scope pics...
I'll pull out my working CGS wavetable this weekend and make some pics. I had one of the last (or the last) set of boards from Ken. |
Oh, we're going to check it out on wednesday! So if it's to much of a hassle don't bother..
But thanks anyway!
I'll report back as soon as I know what I did wrong!
I'm still asuming I've done a really simple error, but I still can't find it.. |
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n.d
Joined: Dec 15, 2011 Posts: 52 Location: Talos IV
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etaoin
Joined: Jun 30, 2005 Posts: 761 Location: Utrecht, NL
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n.d
Joined: Dec 15, 2011 Posts: 52 Location: Talos IV
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Posted: Mon Feb 16, 2015 12:00 pm Post subject:
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Thank you! |
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