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USB communication errors with ADAU1442


I am having problems with USB communications errors with the ADAU1442. The first download works correctly, subsequent downloads occasionally work but more often than not fail. Occasionally a download appears ok but is corrupt in some way.

I have the SCK and SDA pins pulled high with 2k2 resistors to 3V3. The only other device on the I2C bus is the self boot memory. All traces are gaurded and signal integrity looks fine.

Suggestions please?



  • Is this happening on the ADAU1442 evaluation board, or your own hardware? If it's your own hardware, could you share a schematic? Are you using the USBi to communicate from SigmaStudio to the SigmaDSP, or are you using your own microcontroller solution?

  • Hi JeradL,

    This happens with my own hardware using the USBi to communicate from SigmaStudio. There is no micro controller attached to the I2C bus.

    Attached are two schematic sheets. The pull ups for SDA and SCL are on the CPLD sheet along with the programming interface.



  • I don't see anything on your schematics that would be obviously causing your communication issues. Is the ground on your board connected to your PC's ground? If there is a difference between these two grounds, you may see some problems when you have the USBi plugged in. If you have a laptop, you can test this by running your laptop off of battery power (not plugged in).

  • Ground is common to both. There is a ground path through the USBi connector, and through a serial interface elsewhere on the PCB. However, I will try the laptop.

    A reset of the sigma chip usually clears the problem.



  • A reset of the sigma chip usually clears the problem.

    Does this mean that the problem you're seeing only happens when you first power up your board? Are you making sure that all of your supplies have settled and are the correct voltage before you start to boot the IC? You should also be sure that you are providing a clean reset signal to the ADAU1442 on power-up.

  • The reset is cleanly generated with a DS1818. I have no problem programming the device after a reset, the problem is reprogramming it after I have made changes to the design. The link compile download from sigma usually fails on the second download as if the device still retains something from the previous download.

    Having to reset is a bit of a pain as it also resets another processor on the PCB...

  • I wonder if you tried with selfboot pulled low - cos when you press reset, the dsp will set itself master and start loading data from the flash, during which you have two masters on the bus if they are both talking at the same time. The other thing I could think of is to disable all the input and output bclks/lrcks and see if the dsp can generate a sine tone by using the internal bclk/lrck.

  • 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