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Original question:

TAD5242EVM-K: no output after connecting it to an audio amplifier

TAD5242EVM-K: Unable to observe signals from OUT1/2P and OUT1/2M

Jonathan Goh
Prodigy 10 points
Part Number: TAD5242EVM-K

Tool/software:

Hi,

I am currently using the TAD5242EVM-K and I have some questions.

My setup at the moment is: Linux PC playing an audio file through a Evaluation USB-I2S Board for it to get converted to I2S signals, and these signals are passed in to the TAD5242EVM-K. The photo below is the configuration that I am following. I have also verified that the I2S signals are all working fine.

My questions are:

1. When I play the audio file (e.g. 1kHz audio file) from my PC and I observe the signals for OUT1/2P and OUT1/2M, there seems to be no output coming through. Why is this so?

- Only when I changed the USB-I2S configuration to a 16-bit FIFO element, Audio sample size = 16 bits, number of bits per channel = 32, and change the FSYNC to about 49kHz, then the right output signal will show

2. Do the sampling frequencies of my Linux PC and the evaluation board have to be the same value for it work? e.g. both have to be set as 48kHz at 16 bits sample size

Let me know if you need more information.

Regards,

Jon

  • 0
    TI__Mastermind 30791 points

    Hello Jon,

    The first thing was to check to see if I2S is coming to its EVM and it seems you confirmed they are coming to the board ( checked at test points?)

    If you changed USB-I2S configuration and you see some activity, it points to incorrect clocking,  I would think your clks are not set up correctly.

    Make sure your clks comply to the following equation otherwise the part will not work:   

    BCLK= # of Ch.  *  Ch depth  * Fs

    Also for your ref I am including the picture of my EVM, but I would concentrate on the clks to resolve the issue.

    Regards,

    Arash

  • 0 in reply to Arash Loloee
    Prodigy 10 points

    Hi Arash,

    Yes I have confirmed that the I2S signals are going to the board and I have verified at the test points.

    The default BCLK I am running at is 1.536MHz = 2 * 16 * 48kHz. What should the intended clock be? Also, since I am in Target I2S Mode, the MCLK would not affect anything right? 

    Regards,

    Jon

  • 0 in reply to Jonathan Goh
    TI__Mastermind 30791 points

    Hello Jon

    MD3 in  Controller mode is the Controller clock input but for Target mode Short directly to board ground plane.

    Per data sheet the available formats in both controller or target mode are  TDM, LJ or I2S  and  Word Length is  24 or 32 Bits. 

    Try a 24 or 32bit data ( and recalculate the needed BCK) if still you have any issue, then make sure the data format  matches with your jumper setting.

    Most likely your BCLK is too low.

    you can refer to EVM jumpers in my other post to make sure you have them  correct for your data format:

     https://e2e.ti.com/support/audio-group/audio/f/audio-forum/1427515/tad5242evm-k-only-one-channel-has-sound 

    Regards,

    Arash