ADAU1781 attenuates signal

I have an ADAU1781 on a board that I have designed.  I am communicating with it over I2C from a PIC32.  I seem to be able to set up the chip; however, after it is set up it greatly attenuates all signals coming in. 

Without the SigmaDSP programmed, or with the core off for that matter, should the chip pass the signal through transparently? 

If needed I can post the commands that I send over, but basically I set registers 0x4000 ( just turning on the clock ), 0x4002 ( this is set to 0x00 in all six bytes, I'm not using the PLL ), the digital subsystem is turned on via registers 0x4080 and 0x4081, and I set the left and right channels on 0x400E and 0x400F.  Is there something else I should be doing to just get this to pass audio?  Thanks.

  • 0
    •  Analog Employees 
    on Jan 19, 2015 11:35 AM

    Hi,

    I have moved this discussion from the Processors and DSP community to the SigmaDSP Processors and SigmaStudio Development Tool community. Please continue the discussion here.

    Regards,

    Craig.

  • Thanks Craig.  After further inspection it seems that the problem may have been a damaged chip.  I found the tutorial on how to export code from SigmaStudio to a home spun uController.  Even after importing everything from SigmaStudio line for line and in the order that it was given the part still didn't work.  I have removed it from the board and put a new one in its place.  So far it seems a little better; however, the I2C isn't communicating at the moment.  Bad solder joint I think.  These things are a pain to work on by hand.

  • 0
    •  Analog Employees 
    on Jan 19, 2015 8:29 PM

    Hi,

    Let us know if you have any questions as you get your system up and running. Are you using the EVAL-ADAU1781Z or your own board?

    Regards,

    Coleman

  • Hi Coleman:

    I'm using my own board on this one.  All parts on the board are surface mount parts that I reflowed by hand.  During the initial stuffing of the board I misplaced a bluetooth module that has a large footprint.  In trying to get that part off I know I damaged my processor that is close to the BT module and the ADAU1781.  I suspect that the same thing happened to the ADAU1781.  I've put a new ADAU1781 on the board, but so far the I2C is working.  I probably didn't quite solder it right.  And I may have to pull the chip again and try a tactic that might use a little less heat.

  • 0
    •  Analog Employees 
    on Jan 19, 2015 8:49 PM

    Hi Joe,

    Do you have an oscilloscope? I would like to see a capture of an I2C message, to see the signal integrity. Also, are you using a crystal or active oscillator for MCLK? Do you see good signal there?

    Regards,

    Coleman