Hi Geoffrey, I don't understand, I would have thought that the tolerances would have always be defined from the rotational discipline, since that is what the nodes node1, and node2, have been defined with. The spice resistor shouldn't modify the tolerances on the input nodes should it? If the resistor is modeled in spice in v form (V = I * R) then a branch equation node is added for the current, but the tolerance of that inserted node should be determined from the input nodes also (taking the tightest one if they differ). Dave Geoffrey.Coram wrote: > I don't think it's a question of a resistor with rotational ports, > it's a question of those nets being given tolerances defined by > the rotational discipline, rather than electrical. > > -Geoffrey > > > David Miller wrote: >> So I am just trying to understand how this attribute is used. >> The idea behind this is 2 fold. >> 1. it helps the compiler, so that it doesn't raise warnings when it >> sees I am connecting anything other than electrical to a spice primitive. >> 2. it internally tells the simulator to treat the instance differently >> if it can (for example if it can handle a resistor with rotational >> ports). >> >> module test; >> rotational node1, node2; >> >> (* port_discipline="rotational" *) resistor #(.r(1k)) r1 (node1, >> node2); >> endmodule >> >> So when the compiler processes this, it should see that although we >> are instantiating a spice resistor and passing rotational ports, it >> shouldn't raise any warning/error since we have set the attribute >> port_discipline="rotational". >> Internally the simulator may or may not treat this differently >> depending whether or not it has a specific spice primitive for a >> resistor with rotational ports. >> >> Is this how we use this feature? >> >> Cheers... >> Dave >> > -- ===================================== -- David Miller -- Design Technology (Austin) -- Freescale Semiconductor -- Ph : 512 996-7377 Fax: x7755 ===================================== -- This message has been scanned for viruses and dangerous content by MailScanner, and is believed to be clean.Received on Thu Sep 27 08:00:24 2007
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