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Connections between DAI0 and DAI1

Category: Hardware
Product Number: ADSP21569

Hello,

we are trying to replace our ADSP21469 module with a pin compatible ADSP21569 module. We now face the problem, that the module is used in a couple of
different devices each using the pins a bit differently. Because the 20 PIN DAI of the 469 got pin-reduced and duplicated to two DAIs with 14 pins, we need to partition the signals onto two DAIs.

I have a couple of questions:

  1. Is there a difference between taking a clock signal directly:

      PCGA_CLK_O to SPORTx_CLK_I (only within on DAI)

    or going through the pin buffer:

     PCG0_CLKA_O to DAI0_PBxx_I (DAI0_PBENxx_I = HIGH) and from DAI0_PBxx_O to SPORT0A..3B_CLK_I (DAI0) and
     PCG0_CRS_CLKA_O to DAI1_PBxx_I (DAI1_PBENxx_I = HIGH) and from DAI1_PBxx_O to SPORT4A..7B_CLK_I (DAI1)
     
  2. The latter seems to enable usage of PCG clocks across DAIs using the PCG0_CRS_CLKx_O source, but I guess there will be a slight timing difference between the CLK edges on the different ways? Is there anything else to pay attention to?

  3. For another usecase a further indirection is possible when passing the SPDIF recovered clock SPDIF0_RX_CLK_O through a PCG0_EXT_CLK0_I (Bypassmode) and then again distributing it to both DAIs like above. Do you see any dangers here?
  4. In the 21569 Hardware Reference manual at the PCGs I can read this:
    Cross Mode Connections
    The symmetric dual DAI architecture allows cross connections between both PCGs (A,B) and (C,D) to the other DAI. Each PCG (A through D) supports an alternative input clock (PCG0_EXTx_I)(see Figure 24-1 PCG Block Diagram) which can be sourced via a DAI pin buffer from the other DAI. Note however if routing a source (clock or FS) only DAI pin buffer 2 to 20 can be used (DAI pin buffer 1 is no longer available and is replaced by the DAI CRS buffer for the other DAI). See DAI Routing Capabilities for more information.

    Looking at the "DAI Routing Capabilities" Table in the same manual, I cannot see that the cited is possible. The SRU-Plugin for CCES doesn't let me configure this neither.
    Is this an error in the manual or can you explain me how to achieve sourcing any DAIx pin buffer to PCG_EXTx_I?


Kind regards,
Stefan

  • Hi Stefan,

    Please find the replies below:
    Q1 >> Taking a PCGx_CLK_O signal directly to SPORTx_CLK_I is more effectively compare to Clock >>Pin buffer connection to SPORT.

    Q2>>We noticed less time difference between taking a clock signal directly and going through the pin buffer. But it will not be affecting the clock timing of SPORT.

    Q3>>We are checking on this and we will get back to you soon.

    Q4>> You can connect DAI pin to PCG_EXTx_I. Please let us know which pin you are tried to connect. Also, you need to configure PCG source as External.
    Also, we recommend to refer “SPDIF_ASRC_DAC_AudioPassthrough”example from BSP which have SRU configurations.

    “ADZS-21569-EZKIT Board Support Package“ can be download from the below path:
    www.analog.com/.../adzs-21569-ezkit.html

    After installation, example available in the below path:
    <Installation path>\ADSP-2156x_EZ-KIT-Rel1.0.1\ADSP-2156x_EZ-KIT\Examples\drivers\adc\SPDIF_ASRC_DAC_AudioPassthrough

    Thanks,
    Anand Selvaraj.

  • Hi Anand, thank you for your reply. Regarding Q4, I just try to figure out what is possible as we are still planning.

    I am referring to the HRM text "which can be sourced via a DAI pin buffer from the other DAI". The only pin buffers from another DAI that are offered me in the SRU-plugin are the CRS pins (03 & 05) which connect to the OTHER DAI. Further more the plugin also offers me PB01 from this DAI, where the manual says PB01 is not available any more...("(DAI pin buffer 1 is no longer available...)").

    So maybe the text could be clearer in that the EXT_CLKx_I can be sources by exactly the two clock CRS pin buffers from the other DAI, instead of saysing "a pin buffer from the other DAI" (?)

  • Hi Stefan,

    Thanks for your suggestion.

    Regarding Q3, Yes, it  is possible. Also please let us know if you are facing any issue and purpose of  (Bypassmode) SPDIF recovered clock SPDIF0_RX_CLK_O through a PCG0_EXT_CLK0_I?

    Thanks,
    Anand Selvaraj.