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fmak  
#1 Posted : Wednesday, April 16, 2008 9:55:24 PM(UTC)
fmak

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I am interfacing the board with taps from LRCK, BICK MCLK and SDATA from the 5V AK 4351 DAC.
The first three are biased at around 1.6V dc and the last 1V.

Is this safe? I have no experience in I2S connections.
Russ White  
#2 Posted : Thursday, April 17, 2008 5:15:32 AM(UTC)
Russ White

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I really don't know. These are the kinds of things your probably going to have to read the datasheet about or contact Wolfson if its not covered there.

I tend to think it won't work, as those levels seem too high for the logic low state of the inputs. But who knows.

The digital inputs have a limit of VDD + .3V which is 3.6V so your 5V inputs will be too hot.

Cheers!
Russ

Edited by user Thursday, April 17, 2008 5:21:01 AM(UTC)  | Reason: Not specified

fmak  
#3 Posted : Thursday, April 17, 2008 5:57:37 AM(UTC)
fmak

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Russ White wrote:
I really don't know. These are the kinds of things your probably going to have to read the datasheet about or contact Wolfson if its not covered there.

I tend to think it won't work, as those levels seem too high for the logic low state of the inputs. But who knows.

The digital inputs have a limit of VDD + .3V which is 3.6V so your 5V inputs will be too hot.

Cheers!
Russ


Soory, I may have confused you. LRCK BICK and SDATA all measure around 1.6V dc; but I have no idea what the 8804 will take on its PCM inputs. I also measured the dc bias on the transceiver board and they are also 1.6V or therabouts
Russ White  
#4 Posted : Thursday, April 17, 2008 6:34:05 AM(UTC)
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Are you sure there is any bias? You may be measuring a running AC clock signal with your DMM on DC. Which will show up as a small DC voltage.

In any case, your 5V output is likely going to be too high a voltage for the WM8804 unless you reduce it.

Edited by user Thursday, April 17, 2008 6:36:53 AM(UTC)  | Reason: Not specified

fmak  
#5 Posted : Friday, April 18, 2008 8:49:27 AM(UTC)
fmak

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Russ White wrote:
Are you sure there is any bias? You may be measuring a running AC clock signal with your DMM on DC. Which will show up as a small DC voltage.

In any case, your 5V output is likely going to be too high a voltage for the WM8804 unless you reduce it.


Sure, I measured on a scopemeter on two boards, both in spdif in out and pcm in spdif out settings.

I actually tried a digital connection with the AK4351 with 100R taps, but all I get is noise!

I noticed that the Otto switch is back in stock. Can you please send me one as promised.
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