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PCM1863 - DCM format

Hirotaka Matsumoto
Guru 27525 points
Other Parts Discussed in Thread: PCM1863, PCM4204, PCM1865, PCM1864, PCM1862

Hi all,

Would you mind if we ask PCM1863?

When we use DCM format with the PCM1863, is it possible to gather into one TDM?
For example, we'd like to gather 4 ADC input signal into one TDM like as following PCM4204 which shows on the datasheet P19.
http://www.tij.co.jp/jp/lit/ds/symlink/pcm4204.pdf

We could not find it exactly.
So, we need your help.

Kind regards,

Hirotaka Matsumoto

  • 0
    TI__Mastermind 27850 points

    Hi Hirotaka,

    Yes the PCM1863 can do 8 channel TDM. By this I mean it can support talking on an 8 channel TDM bus, a BCK of 256FS is required to operate in TDM mode. Since the PCM1863 only has 2 ADCs it will only be able to contribute 2 Analog inputs to the TDM bus, using a PCM1864 or PCM1865 has 4 ADCs and therefore can output 4 channels on a TDM bus.

    Justin

  • 0 in reply to Justin Bohr
    Guru 27525 points

    Justin san,

    Thank you for your prompt reply.

    Please refer to following file.
    20150225_PCM1863.pdf

    About TDM data format, we have some questions.
    So, could you let us know it?

    Kind regards,

    Hirotaka Matsumoto 

  • 0 in reply to Hirotaka Matsumoto
    Guru 27525 points

    Justin san

    We guess that your days are so busy.
    However, we will appreciate for your cooperation, if you reply it.

    We need your help.

    Kind regards,

    Hirotaka Matsumoto

  • 0 in reply to Hirotaka Matsumoto
    TI__Mastermind 27850 points
    Hi Hirotaka san,

    The PCM186X can use TDM mode in both master and salve mode but dose not need the subframe signal. It is required to have the BCK be 256*fs when in TDM mode. This allows 8 channels to be sent per TDM frame. For the PCM1862, since it only has 2 main input ADCs, you can output just those 2 channels (Ch1L, Ch1R) and the outputs will then go into a high Z mode so that other devices on the TDM bus can drive the line to use the other channel slots. There are registers to modify the TDM TX and TDM RX offsets so that you can choose which TDM channel the PCM186X will read from if any, and which TDM channel it will transmit on.

    Justin
  • 0 in reply to Justin Bohr
    Guru 27525 points

    Justin san

    Thank you for your prompt reply.

    As conclusion, our customer would like to get compiled(at the one frame) datas of  4CH using TDM mode.  
    However, when we use PCM1863(PCM1862), using TDM mode, only datas of 2CH(CHXL, CHXR) that is selected will be sent at the one frame.
    So, in case of PCM1863, the output of data will be 2CH(CHXL, CHXR) using TDM mode at the one frame.

    Is our recognition correct?

    Your days are so busy, but  if you will reply us,  we do appreciate your help.

    Kind regards,

    Hirotaka Matsumoto

  • 0 in reply to Hirotaka Matsumoto
    Guru 27525 points

    Justin san,

    Sorry for troubling you when you are so busy.
    If our recognition is uncorrect, could you let know us?

    Kind regards,

    Hirotaka Matsumoto

  • 0 in reply to Hirotaka Matsumoto
    TI__Mastermind 27850 points
    Hi Hirotaka,

    Yes the PCM1862 and PCM1863 only have 2 main ADCs and therefore can only take in two analog signals and convert them to digital then place them on the TDM bus. This means to get a system with 4 analog inputs that are converted to digital and sent on the TDM bus you would need 2 PCM1862s or PCM1863s. If you would like to do 4 channels per device you will have to use the PCM1864 or PCM1865 which have 4 main ADCs, and would only need 1 for an 4 channel system.

    Since the PCM186X parts require that you have BCK at 256*fs, you will always have the capacity for 8 channels on the TDM bus.

    Justin
  • 0 in reply to Justin Bohr
    Guru 27525 points

    Justin san,

    Thank you for your cooperation!
    We got it!

    Kind regards,

    Hirotaka Matsumoto