ADAU1452 and I2S together
Hi all,
My question is going to be a really basic one, but still, I can't figure out the setting in sigma studio.
About the setup:
WW8804 SPDIF -> I2S eval. board's I2S output connected to ADAU1452 eval. board's SDATA_IN2, LRCLK_2 and BCLK_2 inputs.
The SPDIF has a sampling rate of 44.1kHz and the DSP is the master, using the same sample rate.
If I understood it correctly, it is enough to connect the LRCLK and BCLK to the DSP in order to get the correct clock value, if the DSP is the master, and we now the constant sample rate. Still, I have only noise on the output.
May I ask for some help regarding this problem? I have to do some extra work in the setup inside SigmaStudio, or the problem comes from the incorrect wiring maybe?
Thank you in advance!
Best regards,
Bálint
Audio Signal Processors
adau1452
SigmaDSP Audio Processors
Hello Balint,
There are so many things that can be causing this problem so we will need more information.
First, the I2S data format has to be standard with 1 bit clock delay and 32 bit slot size with 50/50 duty cycle LRCLK. Both the WM8804 needs to be setup this way and the SigmaDSP serial ports as well.
You said the SigmaDSP is the master. This will work for transmitting SPDIF but not for receiving. I took a quick glance at the WM8804 and it does not appear to have a sample rate converter built in. An SPDIF receiver MUST recover the clock from the incoming audio and transmit that clock. It will never be the same as the DSP internal clock unless there is some sort of house master clock for both devices which I have never seen except for older Pro Audio equipment. So I am guessing the Wolfson part has two sets of clock pins, one and input for the SPDIF transmitter and one an output for the SPDIF receiver. This means the DSP needs to be a slave and those clocks and data routed through the sample rate converter inside the DSP or simply have the DSP slave to the incoming clocks.
How this is all setup depends on what the rest of your system needs are. The SigmaDSP clocking is very flexible.
Also, you made no mention of Master Clock. Where is that coming from and what parts are using it?
Since you are wiring together two evaluation boards, you have to be careful how long the wires are and you should be running ground wires along with the clocks and data. A ribbon cable works well to have a clock on one wire with ground on the next then another clock then another ground etc. Alternating ground with all the other pins. You are not trying to run at a high sampling rate so that will make it easier.
So have a look at the WM8804 datasheet a little closer to see how they suggest the clocks be connected.
Then look at our datasheet, and eval board user guide, to see how to use the ASRC (Sample rate converters) in the DSP. It is discussed in the user guide since the eval board has an SPDIF input and that audio has to be sample rate converted.
Dave T
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