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TMS320DM8168: McASP interface

Part Number: TMS320DM8168

Hi Ti,

As I know, The McASP can be initialized for separate transmit/receive sections. It can operate independently.

So if I want to receive the digital pcm from HDMI source and transmit to audio DAC soc via the same McASP interface at a time.

is it possible?

In hardware:

1. Connected Rx clock(AHCLKR, ACLKR, AFSR) for HDMI source and Tx clock(AHCLKX, ACLKX, AFSX) for audio DAC soc.

2. Configure AXR[0] as McASP Rx and connect with HDMI Dout, AXR[1] as McASP Tx and connect with DAC Din

In software:

1. Set TX_ASYNC bit in DAVINCI_MCASP_ACLKXCTL_REG

2. Create two dai link: hdmi dummy codec and DAC codec

How could I use two dai link with one McASP? any example?

Thanks a lot

BR,

Steven

  • Hi Steven,

    Steven Weng1 said:

    As I know, The McASP can be initialized for separate transmit/receive sections. It can operate independently.

    So if I want to receive the digital pcm from HDMI source and transmit to audio DAC soc via the same McASP interface at a time.

    is it possible?

    Yes, this should be possible. You can receive audio data from external HDMI audio source to DM816x McASP axr0 pin, then make the necessary audio data processing if needed, then send this audio data to external DAC from DM816x McASP axr1 pin. Note that a memory (DDR3 or OCMC RAM) will be also involved in this case.

    You can also use digital loopback (audio data stay at McASP module level), but in this case, both RX and TX sections should work in sync, refer to the DM816x TRM for more info.

    Steven Weng1 said:
    How could I use two dai link with one McASP? any example?

    I will make a search and come back to you.

    Regards,
    Pavel

  • Steven Weng1 said:

    2. Create two dai link: hdmi dummy codec and DAC codec

    How could I use two dai link with one McASP? any example?

    I do not think it is possible to use two codecs with the same McASP modile (i.e. McASP2), and I do not find any example.

    The HDMI codec is dummy, what about DAC codec, is it also dummy? If yes, you can use the same HDMI dummy codec for both HDMI and DAC, this is:

    linux-kernel/sound/soc/codecs/ti81xx_hdmi.c - ALSA SoC TI81XX HDMI dummy driver

    See also the below wiki pages, which discuss about dummy codec driver usage:

    Regards,
    Pavel

  • Hi Pavel,
    Thanks for your support!
    So it's a software issue not hardware...the mcasp module seems OK under this usage.
    Thanks a lot.
    BR,
    Steven