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digital In to EVAL-ADAU1701

Question asked by dzingoni on Mar 12, 2011
Latest reply on Jun 16, 2011 by BrettG

Hi everybody,

I'm trying to interface an eval-adau1701 board with an external SPDIF receiver.

According to the documentation of the board I'm using header J7, where all digital signals can be connected:

 

"EXTERNAL DIGITAL AUDIO INPUT
To use the digital audio input port of the ADAU1701, the 
serial data, BCLK, and LRCLK signals must be connected to 
an external source using Header J7. The source needs to be
synchronous to the ADAU1701, thus, the MCLK should be
input to this header as well. On J7, the row of pins along the
edge of the board are ground and the inner row of pins are
the signals. 
Within the SigmaStudio software, the digital input Channel 0
through Channel 7 are accessed in the input cell in Position 2
through Position 9, as shown in Figure 6. Position 0 and
Position 1 are inputs from the ADCs.

"

 

I have a SPDIF board using a cs8416 receiver. This outputs left justified data, with a 256*fs MCLK. Fs is 44100 hz, as the data comes from the SPDIF

ouf of a CD player. According to the above description I have connected BCLK, LRCLK, and serial data, and also MCLK to header J7.

 

Now, problem #1:

you also have to change switch S1 on the board so that MCLK for the chip comes from the header and not from the crystal on board.

What I see is that if I want to compile/link/download a program to the board using the USB link and SigmaDSP interface, the communication fails if the switch S1 is set to use the clock on header J7, while the transfer is OK if I set the switch to use the internal crystal.

I suppose that in this way I can send the software to the board, but then?

Can I switch on the fly to the other position? Do the 1701 accept to change its clock this way maintaining the internal program?

Or am I doing something wrong? What's the correct procedure to use an external clock?

 

Then, problem #2:

the program don't works. I have a simple program with a volume control and out to the internal dacs, just to test that serial data in is working.

Nothing happens. This can be a consequence of problem #1, but in case that the abowe switching procedure is correct, how can I check

that the chip is actually receiving data from the serial data in?

Thank you for your support.

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