ADAU1467 TDM4 mode

Hi,

   my system consists of an ADAU1467 and two PCM3168A codecs, for a total of 8 inputs (4 on each codec) and 16 outputs (8 on each codec).

DSP and CODECS receive both the master clock from a 24.576 MHz external oscillator.

The DSP is BCLK and LRCLK master: it receives and transmits digital audio @96kHz in TDM4 format, using Serial Input Port 0 and Serial Output Port 0, using the following audio digital data lines:

I/O lines DSP pin CODEC
Input 1 - 4 SDATA_IN0 1
Input 5 - 8  SDATAIO0 (input serial port 0) 2
Output 1 - 4 SDATA_OUT0 1
Output 5 - 8  SDATAIO3 (output serial port 0) 1
Output 9 - 12 SDATAIO4 (output serial port 0) 2
Output 13 - 16 SDATAIO5 (output serial port 0) 2

Running a simple DSP application that performs just a input - output routing of the first 8 channels (see the attached project),

- inputs 1 - 4 are faithfully reproduced on the corresponding outputs: if no signal is applied on the input, the outputs are silent and everything works correctly

- inputs 5 - 8 generates the following noise (I took the signal from the analog outputs of the CODEC 1)

I stated it depends on the inputs because if I route input 1 - 4 to output 1 - 4 and 5 - 8 all outputs works fine.

i did a lot of tests before writing here, I'm pretty sure the problem is not in my board layout / schema / power, but it depends on the DSP.

Any suggestion would be really appreciated.

Best regards,

Diego

ADAU1467_passthru.zip