[ibis-macro] Re: ignore_bits and TX vs. RX

  • From: "Todd Westerhoff" <twesterh@xxxxxxxxxx>
  • To: <michael.mirmak@xxxxxxxxx>, "'IBIS-ATM'" <ibis-macro@xxxxxxxxxxxxx>
  • Date: Thu, 28 Jun 2012 09:47:56 -0400 (EDT)

Michael (& all),


I don't believe that the TX should shorten its output by the value of
Ignore_Bits at all . nor should the RX.  The waveform pipeline is the
waveform pipeline.


Ignore_Bits is part of the contract between the model and simulator,
whereby the model declares "the first xxx bits of my output should be
ignored" . which implies that there is output that needs to be ignored to
begin with (clumsily worded, I know, but I can't come up with better at
the moment).


Does that make sense?




Description: cid:EAFF2D52-4B63-4A05-9D24-B96BE375B7E0@eau.wi.charter.com

Todd Westerhoff

VP, Software Products


Signal Integrity Software Inc. .  <http://www.sisoft.com/> www.sisoft.com

6 Clock Tower Place . Suite 250 . Maynard, MA 01754

(978) 461-0449 x24  .   <mailto:twesterh@xxxxxxxxxx> twesterh@xxxxxxxxxx



"I want to live like that "

                                             -Sidewalk Prophets



From: ibis-macro-bounce@xxxxxxxxxxxxx
[mailto:ibis-macro-bounce@xxxxxxxxxxxxx] On Behalf Of Mirmak, Michael
Sent: Wednesday, June 27, 2012 4:31 PM
To: IBIS-ATM (ibis-macro@xxxxxxxxxxxxx)
Subject: [ibis-macro] ignore_bits and TX vs. RX


A deceptively simple question.


Ignore_bits as a parameter can apply to the TX or the RX.  The language of
the specification states that it determines the number of bits to be
ignored by the simulation tool.


In the case where I have a link where only an isolated TX or an isolated
RX, this is easy to understand.  But what happens when I combine a TX with
an RX on the same link where both use ignore_bits?


I would assume that the TX (using GetWave) would provide the tool with a
waveform that the tool would then shorten by the stated number of bits
(say, 21.  But would the RX GetWave then use the shortened waveform in its
own analysis, before the tool reports back an even shorter waveform?


Specifically, if ignore_bits is 21 in the TX, and ignore_bits is 35 in the
RX, does that mean that the final waveform reported out by the tool would
be shorter than the original pattern by 56 bits?


-          MM

GIF image

Other related posts: