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PCM AC3 and DTS loop through.

John Sim
Prodigy 90 points
Other Parts Discussed in Thread: PCM9211, TPA5050, TPA5052

My aim is to use the PCM9211 in a delay project.   So I need to take the TOSLINK output from a DVD player, delay it, and then reproduce it.   So I've got the PCM9211EVM to work with.


I've lifted off W9 to disable data interfering on MPIO_C.   I've also soldered I2S_Enable high to prevent TAS1020 from putting data on to MPIO_C.   RXIN2 is used, and configured through as DIR to output on MPIO_B (AUXOUT).   MPIO_B is looped directly back to MPIO_C (this part will be replaced later with something to hold the data, but for proof of concept for the PCM9211 it is directly looped).   MPIO_C is set for DIT Standalone mode, and for MPO0 output using TXOUT.


My configuration works for PCM audio from a CD, but won't for Dolby Digital (AC3) from a DVD player.   Even if I select DTSCD on register 0x28.


I do wonder about the DIR Channel Status Data Buffer (0x5A) to DIT Channel Status Data Buffer (0x63) but these are not shown as being accessible in the CodecControl software.

Any suggestions as to what I need to look to do further?  Thanks.

  • 0
    Genius 3295 points
    Hi John,

    How much delay are you looking for? If less than 170mS, take a look at the TPA5050/TPA5052 devices.

    Mike T.
  • 0 in reply to Mike Tripoli
    Prodigy 90 points

    Hi Mike,

    I've used those devices for a circuit which had stereo analog audio in and out so it did the delay in between.   But you still need the I2S in and out.   It would do the delay part nicely, but I don't think it would replace the input/output required for TOSLINK.   And you'd still be wondering why the output of the PCM9211 wasn't outputting digital audio that's recognised by the amp.

    Thanks for your reply.

    John.

  • 0
    Prodigy 90 points
    I've read back the receive channel status data buffer and written it to the transmit side and now it seems to be ok with surround sounds. I had to do this in the command scripting page, rather than register inspector. The register inspector refused to take changes.

    Once this was done, my technique works and I've proven that the PCM9211 will work for my application. Now I need to prove the next part of my application!
  • 0 in reply to John Sim
    Prodigy 70 points
    Hi John,

    may I ask which surround stream formats you've tried with the PCM9211? Do you know if it supports DTS and Dolby Digital and/or AC3?