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SRIO cable length and recovered clock

Fawad Nackvi62335
Expert 1080 points

I would like to use SRIO to connect from a box (TX) to box (RX), i.e. not chip to chip or board to board (backplane) with a cable.  Both systems would have a C6757.  I have a few questions

1) Can I drive the SRIO to a length of approx 1m?

2) I would like to use the recovered SRIO clock on the RX.  I see that SRIO recovers the clock but I can't see how I can output this clock and use it locally in the RX.

Thanks,

Fawad

  • 0
    TI__Mastermind 42545 points

    Hi Fawad,

    1) The length of your cable depends on the quality of the cable and the quality of the connectors. The only way to determine whether your connection will work would be to simulate the entire link with the proper models for both the cable, the connectors and the board layout. The SRIO specification provides a mask that must be met at the destination which would include the loss of all of your connections between the boards. 

    2) I'm not sure what you are asking. SRIO is a source synchronous interface that recovers the clock at the receive end and uses that to latch the data. This occurs within the device. The clock is not brought out since there isn't anything external that needs to be synchronized. 

    Regards, Bill

  • 0 in reply to Bill Taboada
    Expert 1080 points

    Bill,

    Thanks for your answers.  If I can't output the "recovered" clock then SRIO is not of use to me.  I see how how the clock is recovered in SRIO but I do have a use of the recovered clock.  The reason is I am planning to send 80 channels of audio sampled at 48 kHz (240 Mbit/s) thru a SRIO link to another box.  On the received side I need to take the received clock and generate a master clock for the audio converters (DACs).  I see I can do this on a serdes signal which sends say a clock and data (parallel mode) and I recover the clock and de-jitter it and derive a master clock from it.  So i thought I could do the same with SRIO.

    Thanks,

    Fawad

  • 0 in reply to Fawad Nackvi62335
    TI__Mastermind 42545 points

    Hi Fawad,

    Unfortunately that clock isn't available to you . The SRIO interface will simply transfer you sample data into memory as blocks. Note that SRIO operates at pretty strict data rates and I don't think you could slave it you the sample clock on your master board. You can establish a new sample clock on the second system but you would have to add some software to handle situations where the buffers overflowed or underflowed. 

    Regards, Bill