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PCM9211: HDMI ARC cable direct connection pin map

Brian Han1
Intellectual 530 points
Part Number: PCM9211
Other Parts Discussed in Thread: TLV3541

Hello,

I'm trying to extract SPDIF audio from the HDMI cable connected to the TV HDMI ARC port.

This will be the only function that I will be using with the PCM9211.

It seemed there was a technical note for the PCM9211 called SBAA300A.pdf, but I couldn't find it anywhere.

I'm assuming that the connection should be like below from the community's information.

My question is

1. Is this diagram correct?

2. Will this drawing be compatible with both HDMI 1.4 ARC and HDMI 2.1 eARC(No Dolby support and some limitation on data rate)?

3. Is there a recommended differential to single-ended converter?

Thanks in advance

  • 0
    TI__Mastermind 23050 points

    Hi Brian,

    Your diagram shows the PCM9211 output as SPDIF, are you using the PCM9211 to mux this SPDIF data or is this intended to convert SPDIF to I2S?

    A few things to mention:

    1) ARC has the option for a single-ended mode, so if you were only planning to use ARC then you wouldn't need a differential to single-ended converter. eARC however, will require this.

    2) It may be possible to interface with eARC if you implement the DE-SE conversion and the data is at slow enough rates (216kHz Max) and only 2 channels are required. This severely limits eARC though because this standard is intended to run more channels at higher data rates to allow for compressed audio transmission over HDMI. The PCM9211 DOES NOT accept compressed forms of audio. Therefore, the PCM9211 may function in limited eARC applications that don't utilize the full eARC capability, but I would not say that it is broadly eARC compliant. This is something I am currently working to correct in the datasheet to avoid confusion.

    3) You can implement the DE-SE conversion in a few different ways. You could use a balun (transformer), but this will require that your source has adequate drive strength. If you want an active implementation you could use a standard op-amp in a difference amplifier configuration. There are a number of high speed amplifiers that are capable of handling this. TLV3541 may be a good starting point.

    Best regards,

    Zak

  • 0 in reply to Zak Kaye
    Intellectual 530 points

    Hi Zak,

    Thanks for the detailed feedback.

    I will be connecting the PCM9211 to an MCU, which will accept SPDIF and converts it to I2S, and MCU will be connected to a stereo DAC. (216kHz is enough)

    *I'm trying to make the MCU act as an audio hub that accepts other peripherals like USB and BT. For HDMI, PCM9211 seemed to be the best choice.

    Maybe I was misunderstanding the ARC and eARC concept.

    I just need the 2 channel SPDIF data from the HDMI ARC. I am not able to process any of the Dolby formats.

    But for the compatibility with the future eARC supporting TV, I thought I was going to need the DE-SE conversion even though ARC supports the SE mode.

    If I can just connect HEAC+ pin to the PCM9211 directly, regardless of the ARC or eARC TV port for the data, then it will be best. But you are saying this won't be possible with eARC?

    If DE-SE conversion is required for eARC then I will try TLV3541 for the work.

  • 0 in reply to Brian Han1
    TI__Mastermind 23050 points

    Hi Brian,

    I dug into the eARC protocol a little more and realized there are some additional challenges. It is actually not possible to use eARC with a simple DE-SE converter because the standard incorporates a common-mode modulation of the signal to encode channel data and control. The eARC protocol requires this feature be supported for communication to be established and unless you are able to do this with your processor this is not something the PCM9211 can support.

    For the ARC case, you could connect the HEAC+ pin directly to the PCM9211 as you mentioned, but unfortunately this will not work for eARC. Some eARC devices are programmed to switch to ARC if they are unable to establish an eARC link, but this is an optional feature so it's not guaranteed your board would be compatible with eARC devices.

    Best,

    Zak

  • 0 in reply to Zak Kaye
    Intellectual 530 points

    Hi Zak,

    Thanks, I think I will focus on ARC for now and wait for another integrated solution for eARC later.

    So this will make it much simpler. Connect HEAC+ to PCM9211 and done!

    I actually changed track and decided to use I2S instead of SPDIF to remove inverter gates.

    Thank You