FPGA Central

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
'1').
Can anybody throw some light to this.

Regards
Kumar

Sounds to me like HDLC. You should consider to do the stuffing on the
serial data, before deserializing it.

kumar wrote:
> 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
> '1').
> Can anybody throw some light to this.
>
> Regards
> Kumar

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 wrote:

> Sounds to me like HDLC. You should consider to do the stuffing on the
> serial data, before deserializing it.
>
> kumar wrote:
>
>> 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
>> '1').
>> Can anybody throw some light to this.
>> Regards
>> Kumar
>
>

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
Gang
"kumar" <[email protected]> wrote in message
news:[email protected] om...
> 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
> '1').
> Can anybody throw some light to this.
>
> Regards
> Kumar

Read demux as MUX . Sorry for typo.

"Gangatharan" <[email protected]> wrote in message
news:c0ci1p$umk$[email protected]..
> 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
> Gang
> "kumar" <[email protected]> wrote in message
> news:[email protected] om...
> > 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
> > '1').
> > Can anybody throw some light to this.
> >
> > Regards
> > Kumar
>
>

Hi Kumar,

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

Andre

[email protected] (kumar) wrote in message news:<[email protected] com>...
> 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
> '1').
> Can anybody throw some light to this.
>
> Regards
> Kumar

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.


Regards
Kumar








[email protected] (ALuPin) wrote in message news:<[email protected] com>...
> Hi Kumar,
>
> on which data rate are the incoming data arriving?
> Which frequency do the data have when leaving the "black box" ?
>
> Andre
>
> [email protected] (kumar) wrote in message news:<[email protected] com>...
> > 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
> > '1').
> > Can anybody throw some light to this.
> >
> > Regards
> > Kumar

See comments below.

-Vikram.

[email protected] (kumar) wrote in message news:<[email protected] com>...
> 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.

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.

> 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 think you should be able to do this by using byte-wide barrel
shifters.

> I would like to hear more inputs regarding the implementation.
>

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