[LAU] open hw soundcard with ext. codec

Martin Homuth-Rosemann linuxaudio at cryptomys.de
Tue Nov 17 17:04:19 EST 2009


Am Samstag, 14. November 2009 schrieb Karl Hammar:
> Folderol:
> > On Sat, 14 Nov 2009 09:34:15 -0500
> >
...
> > On the hardware side, that Atmel development kit (2) looks very
> > interesting as a proving ground as it already has both the network and
> > the 48kHz DAC parts built in.
> >
> > For rough testing it could be used to lock a pair of ADCs. TLC4545ID
> > looks like a good (cheap) possibility here.
> 
> Found it, datasheet at [1], it seems to cost ~12USD. There is no
> "start" pin to be able to simultaneously start multiple converters.
> And you cannot daisychain this chip. [2] can be daisy-chained, but
> with a maximum of eigth channels, but it can be synced.
> 
> If we are going to have multiple analog inputs at higt sample rate,
> isn't it better to have a parallell interface. With spi the number of
> channels will be limited to something like 8 for a 24bit converter.
> Plus that the AT32AP7000/AT91SAM9260 only has two spi-busses.
> 
> Maybe ad7762 [2] could be useful (28 USD),
> 
> > (1) http://www-net.cs.umass.edu/kurose/transport/UDP.html
> > (2) http://www.atmel.com/dyn/products/tools_card.asp?tool_id=4102
> 
> [1] http://focus.ti.com/lit/ds/symlink/tlc4545.pdf
> [2] http://www.analog.com/static/imported-files/data_sheets/AD7764.pdf
> [3] http://www.analog.com/static/imported-files/data_sheets/AD7762.pdf
> 
> Regards,
> /Karl

Hi Karl, hi LAU users

I've followed the discussion about timing and synchronisation - what do you 
think about separation of number crunching and communication (ATNGW100) from 
the "dirty business" of ADC. 
We need the codec, some kind of amplification, a clean power supply etc. to get 
a good S/N ratio - and we need it for a lot of channels. 
There exist many (more or less) pro-audio devices with well documented 
interfaces (SPDIF/AES-3; ADAT; MADI) - a cheap one is e.g. the Behringer 
ADA8000 for about 200 € [1] with eight mic (phantom power) or line inputs and 
eight line outputs. The codecs are 24bit at 44.1/48 kHz [2] 

[1] http://www.thomann.de/gb/behringer_ultragain_pro8_digital_ada8000.htm
[2] http://images4.thomann.de/pics/prod/164573_manual_eng.pdf

Regards
Martin Homuth-Rosemann



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