i2s connection question

[stephan-schulz]

Hi all,

let me warn you first: I am fairly new to DAC design, so flame me if you must...

Here comes the question:

If i get the i2s spec right, it needs three signals to communicate (clock, word select, data). So how come, that some chips on the receiving end only use one??
So, for example if i would like to use the i2s output of an old philips cd-player chip (SAA7220) and connect that to the AK4113, would it work?

Can you suggest any further readin on the issue for me?

Cheers
Stephan

 

[SoNic_real_one]

If it is i2s, there are always 3 signals. They might not be coming all from the same place, (depending which circuit it is the master and which are slaves), they might be called different, but the DAC will get those signals from somewhere .

 

[pilli]

i2s ... three signals to communicate (clock, word select, data).
So how come, that some chips on the receiving end only use one??
So, for example if i would like to use the i2s output of an old philips cd-player chip (SAA7220) and connect that to the AK4113, would it work?
Can you suggest any further readin on the issue for me?

Hi Stephan,
when there is one signal, it is probably SPDIF or some of the similar formats.
You can start with wikipedia
http://en.wikipedia.org/wiki/SPDIF

Read the AK4113 datasheet carefully; looks like it has six "bi-phase" inputs (which is what SPDIF is).


The SAA7220 puts out SPDIF on pin 14 called DOBM, "biphase mark code".

If you go that way, be aware that SPDIF being a "high speed" format, it has precise requirements on the transmission medium, cable, connectors, terminations.
It's something like this: each second, 48.000 samples of 24bits for 2 channels must go through, which makes something in the 2MHz range, where radiofrequency properties of the transmission line become relevant.
(Sorry, this may be not 100% correct, but it gives an idea of things... am a beginner myself)

I think I could hear the difference between an SPDIF link using an audio RCA cable and using a proper 75ohm cable with 75ohm BNC connectors. The former works, it makes the DAC play, but the latter sounds better (wasn't an accurate careful comparison, though...)

Hope this helps a little.

Cheers.

_