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ADAU1761 Audio Codec interfacing issue with MCLK sync

Category: Software
Product Number: ADAU1761


We are using the ADAU1761 audio codec part.

The input to the MCLK is from an onboard Oscillator and is 12.28MHz and interfacing to the controller through I2S and in slave mode.

We have an issue with MCLK and I2S Clock sync issue and are not able to see outputs on Line out.

More details of the connection/circuit can be found in this thread:  RE: Schematic review request for ADAU1761BCPZ Audio-Codec 

The evaluation board has an option of MCLK through an onboard Oscillator and other external options. What was the test setup used with the onboard oscillator?

[edited by: KLN at 6:38 PM (GMT -4) on 18 May 2022]
  • Hello KLN,

    Can you send over your SigmaStudio project file? Then I can look at your setup more easily. 

    What are the details of the serial data going to the 1761? From your frequencies in the other post I assume you are sending 48kHz stereo I2S signals. Rather standard but I want to be sure. 

    Dave T

  • Hello Dave,

     thanks for your early reply,

    we are not using any sigmastudio project.since we are using custom board ,we just have to prove the adc to dac loop back I.e. we are sending an 4KHz square wave through Lin and trying to read it from LOUTP .

    We tried with input to output mixer direct loop of Line input,  no output on LOUTP. 


    RIN-GND and

    LOUTN unconnected

    Here are  the configuration registers

    0x4000 0x0e
    0x4002 0x000000002001
    0x4000 0xf
    0x4015 0x01
    0x400a 0x0f
    0x400b 0x07
    0x400c 0x0f
    0x400d 0x07
    0x4010 0x05
    0x401c 0x0D
    0x401e 0x0D
    0x4023 0xe7
    0x4024 0xe7
    0x4025 0xe7
    0x4026 0xe7
    0x4019 0x03
    0x4029 0x03
    0x402a 0x03
    0x40f2 0x01
    0x40f3 0x01
    0x40f9 0x7f
    0x40fa 0x03

    The above register are on working on same audio codec part present on ZED baord.

  • Hello KLN,

    You need to insert a delay after writing to 0x4002, the PLL register. You need to make sure the PLL is locked before writing to and other registers. 

    So that is one part of this. 

    So I painstakingly entered your register writes into SigmaStudio sequencer. Then I powered up a part so it is at the default. Then I wrote in your register settings. Then I read all the registers into SigmaStudio to see what the signal flow is. It is so much easier to see this in SigmaStudio. 

    Your playback path goes nowhere. You are only sending the aux inputs from the analog section of the input signal path. You have the DACs muted. You have the headphone output all the way down. You have the Mixer 5&6 disabled and turned off. Then the line out gain is all the way down. 

    Here is the signal flow.

    I suggest you setup the flow in SigmaStudio. Then clear the capture window and click "Load all Registers". This will display all the registers in the capture window. 

    Then you can select the entire range, right click and save off the data in one of several formats. Then import that into your software. You can go through them and remove the ones that are not changed from the default settings if you like. 

    Dave T