All,
We have already received a few questions about the (Model_Specific
(Tstonefile)) parameter in IBIS 6.1. To remove any ambiguity – we should also
remove the ‘s4p’ extension from the file name.
Thanks,
Ambrish.
From: ibis-macro-bounce@xxxxxxxxxxxxx <ibis-macro-bounce@xxxxxxxxxxxxx> On
Behalf Of Mike LaBonte
Sent: Monday, November 26, 2018 11:18 AM
To: ibis-macro@xxxxxxxxxxxxx
Subject: [ibis-macro] Re: Usage Dep example
EXTERNAL MAIL
If it has required this much discussion, then we probably need a
well-considered BIRD, for a future spec. I do think that dropping "Rx analog
model" for IBIS 7.0 would be a good idea. It leaves us with an example in which
the purpose of "my_file" is not explained, but at least it doesn't mislead.
Mike
On 11/26/2018 12:48 AM, Muranyi, Arpad wrote:
Mike,
Like I said in my previous email, I initially suggested the same as you, to use
Ts4file and move it up to the Reserved Parameter section, but others in that
meeting felt that it would be too much of a change, and we could just do what
we did, change it to my_file and thereby disassociate the example from the
BIRD158 concepts. We just forgot to change the Description. I think the
easiest
and quickest way to fix this would be to change the Description (and if we still
don’t like it we can file it away as a known issue and address it for the next
revision). Do you think that would be still too confusing?
Thanks,
Arpad
==============================================================
From: Mike LaBonte [mailto:mlabonte@xxxxxxxxxx]
Sent: Saturday, November 24, 2018 7:08 PM
To: Muranyi, Arpad <Arpad_Muranyi@xxxxxxxxxx><mailto:Arpad_Muranyi@xxxxxxxxxx>;
ibis-macro@xxxxxxxxxxxxx<mailto:ibis-macro@xxxxxxxxxxxxx>
Subject: Re: [ibis-macro] Usage Dep example
Yes, we eliminated "TStonefile" because it was not an official means to
designate an on-die model, and we did not want to imply that. But "my_file" is
still described as the "Rx analog model", and that is an impossible example
because only a Reserved_Parameter can do that. Maybe the issue here is that we
have not yet found a purpose for Usage Dep, other than to calculate an analog
model.
Stretching to find an example: maybe a Tx buffer that has presets could have
Dep tap coefficients that AMI_Resolve would report out, based on the preset
input. That would allow the EDA tool to know the coefficients in advance, and
pass them into AMI_Init. But even that is not a great example, because the
preset could simply be passed to AMI_Init, which would report the calculated
coefficients as Out parameters. And Dep parameters are not passed to AMI_Init
anyway, so the EDA tool would never know to pass the coefficients back in. This
would not be a valid example.
Can anyone think of a Model_Specific Dep parameter that makes more sense? If
not, then since we do now have Ts4File, to me it makes sense to use that as the
example. What we have now is confusing. An alternative would be to delete "Rx
analog model. " from the Description in that example, and simply leave it vague
what my_file is for.
Mike
On 11/24/2018 6:36 PM, Muranyi, Arpad wrote:
Mike,
If I remember correctly, “my_file” used to be “Tstonefile” in this example, and
I raised the same questions as you did. Instead of changing it to Ts4file and
moving it to the Reserved Parameters section, it was decided to change it to
“my_file” because the purpose of the file could be all kinds of things, other
than
a BIRD158 style buffer model. We just forgot to change the Description after
we did that. Even though I agree with you, I think since the group decided to
handle the situation this way, we should just correct the Description so that
it would not make people think that this is a BIRD158 style buffer example.
Thanks,
Arpad
================================================================
From: ibis-macro-bounce@xxxxxxxxxxxxx<mailto:ibis-macro-bounce@xxxxxxxxxxxxx>
[mailto:ibis-macro-bounce@xxxxxxxxxxxxx] On Behalf Of Mike LaBonte
Sent: Wednesday, November 21, 2018 9:01 PM
To: ibis-macro@xxxxxxxxxxxxx<mailto:ibis-macro@xxxxxxxxxxxxx>
Subject: [ibis-macro] Usage Dep example
All,
Making an editorial pass through IBIS 7.0, I came across a slightly technical
question. The example for AMI Usage Dep has AMI_Resolve setting the name of the
analog model file based on other inputs:
(Rx_model
(Reserved_Parameters
(AMI_Version (Usage Info) (Type String) (Value "7.0")
(Description "This is a v7.0 AMI file."))
(Resolve_Exists (Usage Info) (Type Boolean) (Value True)
(Description "Indicates whether the executable model implements
AMI_Resolve."))
(Model_Name (Usage In) (Type String) (Value "ignore_me")
(Description "IBIS model name"))
(Rx_Receiver_Sensitivity (Usage Out) (Type Float) (Range 0.0 0.0 0.01)
(Description "Value depends on OP_mode and data rate"))
(Init_Returns_Impulse (Usage Info) (Type Boolean) (Default True)
(Description "Impulse response is returned"))
(GetWave_Exists (Usage Info) (Type Boolean) (Default True)
(Description "GetWave Exists"))
)
(Model_Specific
(my_file (Usage Dep) (Type String) (Value "ignore_me.s4p")
(Description "Rx analog model. Value depends on OP_mode"))
(my_corner (Usage In) (Type String) (Corner "Typ" "Min" "Max")
(Description "Informs the executable model what[ML1] corner is selected
by user"))
(OP_mode (Usage In) (Type Integer) (List 0 1 2 3)
(Description "Operation mode"))
…
)
)
In this example, the Rx analog model is represented with a 4-port Touchstone
file specified by parameter my_file, Both Rx_Receiver_Sensitivity and my_file
depend on the legacy IBIS model name, parameter my_corner, and parameter
OP_mode, which specifies the device operation mode. Rx_Receiver_Sensitivity
also depends on bit_time. Parameters Model_Name, my_corner and OP_mode, having
usage type In, are included in both input parameter strings to AMI_Resolve and
AMI_Init. my_file is of usage type Dep, and its dependency on Model_Name,
my_corner and OP_mode is resolved in AMI_Resolve, which returns the value of
my_file. Rx_Receiver_Sensitivity is of usage type Out, and its dependency on
Model_Name, my_corner, OP_mode and bit_time is resolved in AMI_Init, which
returns the value of Rx_Receiver_Sensitivity.
My question is, now that we have Ts4File to formally specify the name of an
analog model file, should "my_file" above be replaced by "Ts4File", which would
also require moving it to Reserved_Parameters? As it stands, this is not really
a legitimate example. It is the EDA tool that must know the analog model to get
the channel impulse response, and there is no way an EDA tool should be using
my_file, or any Model_Specific parameter, for that. I can't think of any
example where a Model_Specific parameter would need to be Usage Dep.
Mike
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