SigmaStudio 4.5 with ADAU1761

Hi -

I need some guidance on getting SigmaStudio 4.5 DSP core functionality working on my ADAU1761.

I have a custom designed USB analog microphone board with a BF706 and ADAU1761.  I've successfully programmed all registers in the ADAU1761 manually via the BF706.  The mic and design work very well and as expected.  I have also successfully used SigmaStudio 4.5 to generate and load an image into the ADAU1761 via BF706 with the same registers I manually programmed using Analog Devices provided code adi_adau1761_SigmaStudioLoad() in adi_adau1761.c.  The problem arises when I simply change the Serial Output Route Control register in SigmaStudio from "ADCs to Serial Outs" to "ADCs to DSP to Serial Outs", enable DSP, set DSP run ON, and add simple ADC L/R input to Dig0/1 serial outputs schematic routing as shown below.  The serial output data is trash (periodic large scale value swings).


1.  See attached SigmaStudio 4.5 project files.  What am I doing wrong that prevents the SigmaStudio image with DSP core enabled from working on ADAU1761 as expected?  Are there additional registers that need to be set to use the DSP core?

2.  I believe SigmaStudio 4.5 does not correctly generate ADC Control 0 register output.  The "Dig Mic In Select" GUI box is backwards.  In other words, for ADC use, "Mic In" needs to be selected in order for INSEL bit in register 0x4019 to be a 0 (0 = digital microphone inputs off, ADCs enabled).

Thanks in advance!



Top Replies

  • 0
    •  Analog Employees 
    on Oct 8, 2020 8:42 PM

    Hello Dave,

    What is the master clock frequency?

    Is the serial ports a master or slave?

    If they are a slave then is the source using the same master clock?

    I will look at the project now.

    Dave T

  • 0
    •  Analog Employees 
    on Oct 8, 2020 8:53 PM in reply to David_Ashman

    Thanks David, 

    Is it exactly 24MHz or 24,576MHz?

    Dave T

  • Exactly 24MHz.  I set up the internal PLL in fractional mode to obtain 48kHz sample rate.

  • 0
    •  Analog Employees 
    on Oct 8, 2020 9:15 PM in reply to David_Ashman

    Hello Dave,

    Yes, that all looks good in your project. 

    First, I should mention that the register for the MIC verses the ADC is just setup in a horrible way. I can say that because it was done before I was here. The text in the field is "MIC IN OFF" and "ADC IN OFF". That alone is confusing but to make things worse when you deal with Windows and how it scales text size based on user settings and monitor resolution I often see some of the text cutoff. So you cut off the text and all you see is "MIC" and you do not see the "OFF" making it look like it is backwards. I certainly would have changed the labels on the buttons but there is no changing it now. 

    For the other issue. I am not seeing anything popping out at me as to why you are seeing this. I do notice that the signal going to the headphone or line outputs is not just the DAC but it is the DAC with the analog feed forward of the mic signal on the input side. So if you are taking the serial output and turning it around to the serial input to go to the DACs then this might be part of the issue. But this would just cause phase issues etc., not loud spikes in level. 

    So it was OK when the ADCs are going directly out of the serial port? 

    One other thing to try is to setup an oscillator in the DSP and send that out of the serial port. This will simplify some things. You can also send the ADC to the DACs as an experiment. 

    Dave T