🚀 go-pugleaf

Todd: My mail to you bounced. So I'm posting my reponse.

>
>~-----------  ---------  ---------  --------   --------  --------  --------
>~|8        |--|Analog |--|Filters|--|      |---|      |  |      |  |      |
>~|Audio    |--|Multi- |  |  and  |  | ADC  |   | DSP  |--| DAC  |--|Filter|
>~|channels |--|plexors|--|  S/H  |--|      |---|      |  |      |  |      |
>~-----------  ---------  ---------  --------   --------  --------  --------
>            ^^                              ^^^
>	Eight lines here.		There should be two lines since it
>					is a dual ADC.

I don't have all the specs yet. I hadn't had a chance to read the
article. The two observations you made above are correct.

>
>Sounds like it might be feasible.  Does it have serial or parallel output?
>
>Serial
>	44.1 kHz * 4 channels * 16 bits/channel = 2.822 MHz
>
>I think the 56000 can handle this.  Only half of what you need, though.
>You might be able to do it with the TM$32030, as it has two serial inputs.

Even if it were serial I'd probably just shift it into shift registers
and read in the parallel outputs when all of the bits of a complete
sample has been shifted in.

>
>Parallel
>	Either 56000 or 32020 can handle this, if you can figure
>out a way to merge the data streams.
>
>~If samples can be obtained for ~$50 then a box for between $200 to $300
>~could be realized. If the DSP is fast enough then another ADC could
>~easily be added for a grand total of 16 channels.
>
>Your biggest problem is that the samples are not arriving at the same
>time.  Actually, I guess you could use an interrupt routine to store all
>the samples, then have the DSP act on them when all have arrived.

That's exactly what I was thinking. Something along these lines:

Sample 1
         Sample 2
                  Sample 3
                           Sample 4
                                    Output of mix of the 4 above samples.

--------Time Axis--------->

>
>Remember that since you are using an analog MUX, the samples can't all
>be done at EXACTLY the same time, so there will be a slight delay between
>all of the channels.

I'm brand new in this domain. I have no clue what the effect of the
delay between channels will be. Can you give me an idea?

>
>Also, if it is serial, you'll have to use TWO 56000s and have them
>talk to each other (not really that hard).  Could do some killer
>filtering, though.

Again with some parallel shift registers that problem disappears.
Right off the top of my head I think you can clock a 74LS164 at
30 Mhz so the speed is not a problem.

Another reponse I saw indicates that a 56001 wouldn't be able to handle
mixing 8 channels much less doing any kind of EQ, reverb, etc. He
suggested a DSP for each channel. I was of course in pain as this is
strictly hobby material for me. Can you give me an idea of how much
processing power a 56001 has? An estimate of how much of the above
(getting data, mixing, providing effects) a single 56001 can do would
be quite helpful. 2 I'd be willing to deal with but my whole concept
is to reduce the parts count to a fairly small board.

>
>There might be some chips from AT&T that are cheap and have two
>synchronous serial inputs.  The TI chip I mentioned is expensive.
>

Also thanks for all of the articles you've been posting and the
server (which I haven't had a chance to use yet). It's all been
quite informative. Keep it up.

Thanks also for the reponse. I'm saving all of the them and
will summarize the results in a little while.

BAJ
-- 
Another random extraction from the mental bit stream of...
Byron A. Jeff
Georgia Tech, Atlanta GA 30332
Internet:	byron@pyr.gatech.edu  uucp:	...!gatech!pyr!byron