external ADC/DAC setup with ADAU1701

Bazeman Question

Oct 2, 2013 00:00

Hi guys,

I hope you could help me...

I'm developing a dsp board with the adau1701 dsp and external ADC (PCM1804) and 2x DAC (PCM1798), so 1input ch/4output ch setup.

I have read in the datasheet of the adau1701 that output_LRCLK (MP10) should be hardwired externally to input_LRCLK(MP4) and output_BLCK(MP11) should be hardwired externally to input_BLCK(MP5), Is this correct?? Also my understanding is that the "looped" LRCLK line and the "looped" BLCK line should be connected to both LRCLK and BLCK pins of the ADC and DAC converters. Did I understand this right? Is any "extra" buffer hardware necessary on these lines, like the buffer on the master clock, for example, to drive the extra adc/dac's??

Then another question related to the previous one, is how to set the ADC.... Should I choose to set it as master or slave? And if I set it to master do I still need to make the loop between in and outs on the adau1701?

If needed I will make a schetch of the setup and upload it. EDIT: I allready posted it ;-)

Thanx.

Bazeman

external

blck

Audio Signal Processors

dsp

adc

lrclk

SigmaDSP Audio Processors

adau1701

dac

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EEtwidget Reply

Apr 16, 2014 00:00

Hello Bazeman,

Did you ever test your config? I am in the beginning stages of investigating a similar config although Im after 2in/4out with external ADC/DAC

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Yagami Reply

Apr 17, 2014 00:00

Hi Bazeman,

If I understand, you want the ADAU1701 to be the master, and your external ADC/DAC will be slaves. Let me know if that's incorrect.

First, two important points:

The ADAU1701's serial input port must always be a slave. That cannot change.

However, the ADAU1701's serial output port can be either a slave or master.

In order to make the ADAU1701 a master to the outside world, you need to do the following:

-Set up the serial output as a master

-Set up the serial input as a slave

-Connect OUTPUT_BCLK to INPUT_BCLK and connect OUTPUT_LRCLK to INPUT_LRCLK.

Just run a trace between those pins to loop-back the DAC clocks to the ADC. There is no buffer or anything required in hardware.

Now, set the serial output as a master in the configuration registers. Also set your external ADC/DAC as a slave.

That should work!

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EZAdministrator Reply

Aug 2, 2018 00:00

This question has been assumed as answered either offline via email or with a multi-part answer. This question has now been closed out. If you have an inquiry related to this topic please post a new question in the applicable product forum.

Thank you,
EZ Admin

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