Arpad: A clarifcation per suggestion 1. is reasonable. You can make proposals regarding declaring the port type for user-defined ports. I think this will take some work and require revisiting a lot of old issues since a method already exists for converting ports using D_to_A and A_to_D. So, some implicit declaration method is already available. Bob Muranyi, Arpad wrote: > Hello IBIS fans, > > We discovered a potential problem with the port types when using > [External Circuit]s. > > The "Ports under [Model]s" section of the spec discusses the naming > convention of the reserved port names used with [External Model]. > > | The first letter of the port name designates it as either digital ("D") or > | analog ("A"). Reserved ports 1 through 13 listed above are assumed or > | implied under the native IBIS [Model] keyword. > > Later, the "Ports under [External Model]s" section describes the port name > rules for [External Circuit]s: > > | The [External Circuit] keyword allows the user to define any number of ports > | and port functions on a circuit. The [Circuit Call] keyword instantiates > | [External Circuit]s and connects their ports to specific die nodes (this can > | include pads). In this way, the ports of an [External Circuit] declaration > | become specific component die nodes. Note that, if reserved digital port > | names are used with an [External Circuit], those ports will be connected > | automatically as defined in the port list above (under [External Circuit], > | reserved analog port names do not retain particular meanings). > >>From these sections of the spec we know how to deal with the ports of > [External Model]s, i.e. it is known what their type is, but there is a > problem with [External Circuit]s. > > Other than the usage of the reserved digital port names, there is no way > of knowing what the port type is for a user defined port name, because we > do not have a mechanism to declare port types in IBIS. Unfortunately the > [Node Declaration] keyword doesn't do more than list the die nodes and/or > pads, so this keyword would not be useful to find out what the type of a > port may be that is connected to it. > > This is a problem, because some tools need to know the type of a port in > order to know how to connect things. Looking into the [External Circuit] > to find out the port type may not be as easy as it sounds either if only > compiled (or encrypted) models are available. > > I would like to make two suggestions: > > 1) If the "first letter rule" was only intended to apply to the reserved > port names (to be honest, this is not 100 % clear to me from reading the > spec.) we need to write a clarification BIRD to clear this up. > > 2) If the "first letter rule" doesn't apply to user defined port names, > I would propose that we invent a port type declaration mechanism to declare > the user defined port types. > > Any comments or questions are appreciated. > > Thanks, > > Arpad -- Bob Ross Teraspeed Consulting Group LLC Teraspeed Labs 121 North River Drive 13610 SW Harness Lane Narragansett, RI 02882 Beaverton, OR 97008 401-284-1827 503-430-1065 http://www.teraspeed.com 503-246-8048 Direct bob@teraspeed.com Teraspeed is a registered service mark of Teraspeed Consulting Group LLC -- This message has been scanned for viruses and dangerous content by MailScanner, and is believed to be clean. -------------------------------------------------------------------- |For help or to subscribe/unsubscribe, e-mail majordomo@eda-stds.org |with the appropriate command message(s) in the body: | | help | subscribe ibis <optional e-mail address, if different> | subscribe ibis-users <optional e-mail address, if different> | unsubscribe ibis <optional e-mail address, if different> | unsubscribe ibis-users <optional e-mail address, if different> | |or e-mail a request to ibis-request@eda-stds.org. | |IBIS reflector archives exist under: | | http://www.eda-stds.org/pub/ibis/email_archive/ Recent | http://www.eda-stds.org/pub/ibis/users_archive/ Recent | http://www.eda-stds.org/pub/ibis/email/ E-mail since 1993Received on Wed Mar 26 15:59:02 2008
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