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TLV320AIC3120EVM-U: Eval Board Requires Enumeration?

Jacob Handy
Prodigy 120 points
Part Number: TLV320AIC3120EVM-U
Other Parts Discussed in Thread: TLV320AIC3120

I have a test set up where an External MCU programs the Eval codec, where I receive audio from the headphones port and through the i2s (which is sent over the usb to the computer). Works great. I tried to use this same setup but with battery power and no USB connections, but I no longer get audio out of the headphones. Does the eval board require a USB connection to operate? Or does the I2S stall the system waiting for the USB controller MCU to request data?

Thank you,

  • 0
    TI__Guru 62035 points
    The TLV320AIC3120 will work fine in your end application when working this way but the EVM is meant to be used as a development environment for the CODEC and not so much as a way to wire the CODEC into an external processor. Without the USB connection you may have some contention on the communication buses due to the missing USB power. If you're really looking for a way to communicate with the AIC3120 on the EVM only through an external processor you may consider cutting some of the traces to the other circuitry or removing some of the ICs that normally provide the communication.
  • 0 in reply to Collin Wells
    Prodigy 120 points
    Which bus would suffer from not having USB? does the USB controller hold the I2S bus in an odd state until it gets USB connectivity?

    I'm applying my battery power to the V bus, so the V bus is not getting 5Vs but the LDO's are still providing the proper voltages for the rest of the system. According to the schematics only the LDO's and SP(L/R)VDD get voltage directly from the VBus.

    The USB controller is still providing a clock on MCLK, and i'm set up to use the PPL on the codec so it seems odd that the codec wouldn't provide the headphones output per the programming. As far as I can tell I'm not getting any contention on the I2C bus when I have my external MCU program the codec. I program the codec well after any initialization the USB controller uses the I2C bus for.

    Thank you,
    Jacob
  • 0 in reply to Jacob Handy
    TI__Mastermind 30030 points
    jacob,

    Can you clarify your test setup?

    I understand that you initially set the EVM connected to your computer, and you were able to play audio from the computer and hear it on the headphones. But if you disconnect from the USB audio source, where does the audio data come from? is your external processor providing BCLK, WCLK and Din?

    The TAS1020B usb audio processor will not provide BCLK or WLCK unless it connects to a host. The MCLK will remain active.

    best regards,
    -Steve Wilson
  • 0 in reply to Steve-Wilson
    Prodigy 120 points

    I'm very sorry for the confusion. I receive audio input from a microphone connected to the codec. I then process the audio and output it to both the, I2S to the PC, and to the Headphone amp output of the codec. 

    So when I tried a battery set up I was hoping that the headphone output would still provide audio output, but it doesn't. The MCLK is still active so I would have thought that the codec would have continued to process and output audio on the headphones, while the I2S channel was waiting for the master I2S to request data (in this case the I2S would wait indefinitely because there is no host to request audio data).

    Thank you,

    Jacob

  • 0 in reply to Jacob Handy
    TI__Mastermind 30030 points
    Jacob,

    one solution would be to configure the codec as the I2S master. then it would provide BCLK and WCLK.

    best regards,

    -Steve Wilson
  • 0 in reply to Steve-Wilson
    Prodigy 120 points
    Steve,
    So having the I2S hanging like this stalls the codec?
    Thank you,
    Jacob
  • 0 in reply to Jacob Handy
    TI__Mastermind 30030 points
    Jacob,

    The internal DSP needs like half a frames worth of clock cycles to enable. This is just at startup. if you quickly turn on master mode, then turn it off, that would work, or you might be able to just short MCLK to BCLK briefly to see if that does the trick.

    best regards,
    -Steve Wilson
  • 0 in reply to Steve-Wilson
    TI__Mastermind 30030 points
    Hi Jacob,

    I just wanted to check in with you on this issue. were you able to get this working?

    best regards,
    -STeve Wilson