ADAU1701 I2S In - Stereo Out
Hi There,
My project consists of ADAU1701 as a slave feeding I2S signal from another IC (HDMI converter - EP94Z3E). The 1701 receives the I2S and outputs it as an analog stereo. Digital IN, Analog OUT. I have verified the four signals coming out from the HDMI - MCLK_IN, INPUT_LRCLK, INPUT_BCLK, SDATA_IN to be present (haven't verified yet if it's correct) under a scope but the output from the 1701 is just pure NOISE. I have tried both the finished board and the MINI evaluation, neither output is eligible.
How can I verify if the DSP program is correct (routing and hardware config)? Is there a way to verify that the digital input coming in is correct?
Attached are the hardware config from the studio.
Regards,
Dan
Audio Signal Processors
i2s
SigmaDSP Audio Processors
adau1701
Hi Dan,
It looks like nobody has picked this up yet, so I'll give it a shot!
First of all, your project and register settings appear to be correct. I can't find any issues there.
The first question, a quite simple one, is: "Are the BCLK, LRCLK, and SDATA signals synchronous to the MCLK signal?" Yes, it's a simple question, and since all signals are coming from the same IC, I assume the answer is yes, but, in engineering, it's never safe to assume. I would suggesting checking this to confirm.
The second question, a hugely important and slightly more complicated one, is: "Is the audio data output from the HDMI receiver raw or encoded? My guess, unfortunately, is that it is encoded in some manner, and requires a decoder. Even though the IC you're using is converting the samples to an I2S serial data stream, there's no guarantee that the data contained therein isn't encoded. My bet is that it is indeed encoded, which means it will appear as just random sample data to the SigmaDSP, which will be output as pure noise.
Anyway, give those two questions some thought and get back to me if you have any ideas!
Yagami
Dear Yagami,
The second question is spot on. Yes, the signal from the HDMI is encoded, so we decided to put a decoder before feeding the signal to the Sigma DSP. Since it's too costly to have the sigma DSP than a decoder, we decided to replace the sigma with a decoder.
Thanks a lot for the detailed and informative reply Yagami! It helps a lot!
More power to!
Regards,
Dan
I have this problem too. I'm using a ADAU1452 Eval, plus a EP94Z3E Board .
This module is an HDMI Audio extractor. It allows to recover the digital audio stream of a digital HDMI source (including MHL) towards a digital coax port / optical or HDMI (I2S via HDMI).
It's got a decoder in it.
It has a function of ressampling to select between an output 2-channel / 5.1 channels or audio output corresponding to the input (bypass).
When I switch to 2-Channel I get correct signals via I2S .
But when I switch to Multichannel I get only noise on the two channel, on the other six is nothing.
Hello,
Look at the data on a scope. If the clocking is not right and the formatting is not right you can get this noise. So first step, let's look at the structure of the data and clocks. Then once we are certain we have the settings correct, then if it is still noise then the data is encoded.
So take the screenshots I asked about on your other post.
Dave T
Please log in to reply.