Bit-Stuffing on parallel 8 bit data

Discussion in 'VHDL' started by kumar, Feb 9, 2004.

  1. kumar

    kumar Guest

    Hi all,

    Can bit-stuffing be done on a parallel incoming data? Is there any
    flow/algorithm to implement it.

    A black box gets 8-bits of parallel data with a max 1024 bytes is
    given to which bit-stuffing logic has to be implemented and the
    bit-stuffed parallel data is given out of the black box.
    | |
    |parallel |
    ----->|bit-stuff|----> 8bit paralle data with bit stuffed
    | |

    Bit stuffing is done for every 6 consecutive bits being one(logic
    Can anybody throw some light to this.

    kumar, Feb 9, 2004
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  2. kumar

    Ronald Hecht Guest

    Sounds to me like HDLC. You should consider to do the stuffing on the
    serial data, before deserializing it.
    Ronald Hecht, Feb 9, 2004
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  3. kumar

    Ronald Hecht Guest

    Ups, my comment was for destuffing. When doing stuffing serialize data
    and then do the stuffing. If this is for HDLC the stuffing should be the
    last thing to do together with flag-insertion.
    Ronald Hecht, Feb 9, 2004
  4. Mike Treseler, Feb 9, 2004
  5. kumar

    Gangatharan Guest

    I do believe this is HDLC.
    I had done this few years back.
    I see it as set of demuxs and adders controlling the muxing. May need
    pipelining depending on the clock speed.
    Also need to consider the requirement for required increase of bandwidth in
    the output due to insertion.
    So you may need to study your overall system and indentify solution
    appropriate to yours.
    Hope I gave you some idea.
    with regards
    Gangatharan, Feb 11, 2004
  6. kumar

    Gangatharan Guest

    Read demux as MUX . Sorry for typo.

    Gangatharan, Feb 11, 2004
  7. kumar

    ALuPin Guest

    Hi Kumar,

    on which data rate are the incoming data arriving?
    Which frequency do the data have when leaving the "black box" ?

    ALuPin, Feb 12, 2004
  8. kumar

    kumar Guest

    Hi Andre,

    Well the black box should work around 100MHz. Hope this is helpful.
    But i am still worrying as to how can i do pipelining, since i have to
    disable to the clock while bit stuffing is happening. It looks pretty
    clear that for serial Bit-Stuffing the logic is well known.

    What bugs is the possiblitiy of doing a parallel bit-stuffing? Is
    there a way in which it can be implemented?

    Well i went through the link specified earlier for this question,
    which speaks about byte stuffing.

    I would like to hear more inputs regarding the implementation.

    kumar, Feb 13, 2004
  9. kumar

    Vikram Guest

    See comments below.


    Assuming HDLC, worst-case bit stuffing can result in doubling of the
    data width. So, one easy way to do this is to read 1 word every 2
    clocks, so that no overflows occur.
    I think you should be able to do this by using byte-wide barrel
    --- <snip> ---
    Vikram, Feb 17, 2004
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