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  1. #1
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    OSERDES implementation and connections

    Hi All,
    I am new at designing and implementing serdes in design.
    I have a high speed data stream to send at high bit rate(working on zynq ultrascale), so i need to implement a OSERDESE3 for that.

    i need to know the following.

    1) what is Gearbox and why it is needed and how will i instantiate it ?
    2) How exactly will i connect the high speed serial data to parallel input pins of oserdes ?

    Thanks
    Mohammed Alauddin

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  2. #2
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    Re: OSERDES implementation and connections

    What device will the Zynq talk to ?



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  3. #3
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    Re: OSERDES implementation and connections

    The "gearbox" is used to align the input bits into output words and also to remove extra encoding overhead. For example, 8b10b's overhead or 64b66b's overhead. For the output, the gearbox adds this overhead to the bitstream.

    For the 8b10b example, the serdes inputs would look like: (kkdddddd) (ddkkdddd) (ddddkkdd) (ddddddkk) (dddddddd) and then this repeats. (here, k = control bit, d = data bit) 4 bytes of data are transferred in 5 cycles for this example. The gearbox likely also generates a "request data" that goes low once per five cycles.

    The input gearbox does the same basic thing, although there are 10 input cases for where data/control could be. The gearbox is responsible for aligning the data on word boundaries. For this example, it would output 4 bytes per 5 cycles assuming 8:1 serdes. The gearbox would likely generate a data valid which would be true four out of five cycles, after alignment has completed.


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