Digital Delay Possibility

[modsquad]

Okay I'm expanding my horizons and came across this chip M65830BP/FP.  It defaults to 20ms delay but is controllable.  My question is could you use it to build an adjustable digital delay pedal?  I may be posting this in the wrong forum, maybe DSP.  Because its a digital delay does that mean you have to control it by sending commands or is it controllable by voltage, etc?

[Seljer]

digital delays are digital in the sense that convert the audio signal into a digital format (1s and 0s), they delay that part, then convert it back into audio
and you can build an adjustable digital delay pedal, all simple delay projects that use the PT2399 are digital delays (Rebote and PT80), its just that it isn't a very high fidelity chip (at least on the longer delay times) so it sounds rather analog in the end.


looking at the datasheet for the one you posted, it does 0.5ms to 32ms of delay, not really enough for a delay, but enough for a chorus or flanger
as far as I can tell, the way to set delay time is slightly more complicated (you can only set the delay time in 0.5ms steps with string of digital data coming from a microcontroller?  ).... I wouldn't really know what to do to hook an LFO up to it and make a chorus/flanger/vibrato but I'm pretty sure some of the more knowledgeable people on here would. You'd just set the delay time to be fixed and add the LFO to the main processor clock?

[modsquad]

Doing a little more research into delays I came across an interesting set of projects one a digital and one an analog:

http://lupinesystems.com/guitar/analog/

[R.G.]

And another flower blooms - 

The only problems with those delays are that the analog one is based on SAD1024's, and the digital one is complex and only 8 bits of resolution, so you only get 48db signal to noise.

[modsquad]

From what I gather then the SAD1024 is prone to being noisy?

So what SNR would be minimum acceptable and I take it the analog to digital conversion is the main culprit for inducing the noise?

OMG, I am beginning to scare myself.

[Threefish]

Freaky. Am I happy to read your post Modsquad!!! There I am with no replies to my query to the forum on the same M65830 chip http://www.diystompboxes.com/smfforum/index.php?topic=56616.0 , and I come across your post!

So, have you come up with anything more on that chip? I've done a fair bit of net research and found very little. With only 20ms to play with, I'm heading down the Chorus path by the look of it. Though I'm yet to find out how to easily modulate the delay time for a chorus sound. There are a couple of projects in Silicon Chip magazine that have used this chip, and at least one of them has variable delay time. From what I understand the default delay time is 20ms - the app note circuit is pretty minimal, and I'm guessing that deviating from the setup presented there is tricky. Have a look at the other link in my thread.
I'm wondering if playing with the modulating/demodulating caps (off pins 16 and 20) or (removing???) the 2Mhz crystal (which is apparently there in aid of accurate timing of the oscillator, though I'm yet to find more info on this) could get me delay time accuracy bad enough for a chorus sound (ie - not constant).
I should be able to get hold of those other articles on that chip in the next couple of days, though I'm not expecting anything on the delay time adjustment that's simple. I'll report back.
Anyone got anything to add??