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66AK2G12: Noisy output generated when using MCASP_Audio_evmK2G_c66ExampleProject

Part Number: 66AK2G12
Other Parts Discussed in Thread: EVMK2G, AUDK2G

Hi,

My customer is using audio example (MCASP_Audio_evmK2G_c66ExampleProject, not AUDK2G add-on but AIC3x on-board codec version) on their K2G EVM.

When running the example, audio loopback itself is working correctly, but the problem is that the output is a bit noisy. There is no specific method to recreate the issue -- Just compile the example and then run it on the target board. I noticed some noise was still existing even if there was no input. You could hear it just connecting your ear phone to EVM line out without input source. Could you please try it out at your setup and see if there was wrong in the existing code, especially, codec initialization ?

Best Regards,
NK

Side note:
- PDK version is 1.0.9 which is bundled in the latest ProcSDK RTOS

  • The team is notified. They will post their feedback directly here.

    BR
    Tsvetolin Shulev
  • Hi NK,
    I checked with the audio expert that worked with the EVM team on the K2G EVM and he stated that the AIC3x doesn't have any appreciable noise if it is working correctly. He suspects that there may be a problem with the EVM. Do you have more then one EVM for comparison?
    Regards, Bill
  • Hi Bill,

    I have two K2G EVMs (Both are Revision D1.3) and I obviously hear the noise on them when running the example. Please note i did not any modifications on the existing code. For example, please try 4Khz sine wave input and hear the loopback-ed output. You should hear obviously the distorted sine tone on your setup if the EVM revision is same.

    Best Regards,
    NK

  • Looked like much distorted for higher frequency tone than lower one.
  • Kawada-san,

    I have tried the MCASP loopback test (PDK_1_0_9)that you are running at your end on two different EVMs and don`t see any noise on the output of the AIC3106. In my setup I am using 2 feet stereo cable and using my phone to input data into Line in. Both with normal audio or with Sine wave, I am not seeing any issues.

    Can you try to check your audio source and input/output cables and see if that is root cause for this issue.

    Regards,
    Rahul
  • Hi Rahul-san,

    It`s curious that you could not recreate the issue at your setup... I`ve already validated that my playback environment is valid. It is same as yours. I`m using my iphone with running tone generator application. First, I validated my ear phone worked without any noise when 4Khz sine tone playback. Yes, it worked. My iphone and app and ear phone are all fine for the test. Next I checked iphone -- line out cable -- speaker connection and it also worked fine. Now i should be able to test iphone -- line out cable -- K2G EVM --- ear phone connection, but the result was not good ; 4KHz sine tone is obviously distorted (It sounds like tone, but not pure and clear one).

    Best Regards,
    NK

  • So did you recreate the issue at your end ? Or, not reproduced yet ?
  • Kawada-san,

    We are not able to reproduce the issue. Is the issue specific to the way the input is generated. Can you zip up the audio file that you are playing back on the loopback that you described in your earlier post so we can use that to observe the issue.

    We played stereo file generated as combination of sine as well as general music and didn`t observe the issue so I am not sure I can comment on why this is observed.

    Regards,
    Rahul
  • Rahul-san,

    Here is the file from the customer.

    • sweep_raw.wav : Input file (sweep signal)
    • sweep_talkthrough.wav: recorded audio output (loopbacked  audio signal) for the above
    • waveform.png : audio plots in some instance

    Best regards,
    NK

    sine_sweep.zip

    EDIT:
    Because AC adapter is not included in EVM delivery, we are using such kind of AC adapter. Just for your information.

  • Kawada-san,

    thanks for providing the audio files that were used for testing by the customer. I am not going to be able to look at this issue till later in the week.
    I will provide you an update based on my observations by the end of this week. Sorry for the delay.

    Regards,
    Rahul