Hi guys, The use of a directive sounds interesting, but in the case of attaching routing parameters to a net, I wonder how it differs from just attaching an attribute.
IIRC, when doing high-speed stuff using the Viewdraw -> Allegro flow, I just had to attach routing attributes to the nets in order to set things like diffpair length tolerances and the like. For example, I just double clicked on the relevant net, and added DIFFPAIR=VIN to two different nets (VIN_P and VIN_N, say) to cause Allegro to know that they were related to one another. Then I added a rule like DIFFPAIRLENGTHTOL=10 to those nets to cause Allegro to make their lengths match to within 10 mil. What does a directive do that is different from this? Is there something else a directive gives you, like the ability to switch it on and off from the command line? Stuart > > Hi Dan, > yes, I think it can be used for that. gnetlist now builds two netlist: > the traditional one and another netlist of objects with the attribute > "graphical=3D1" set. > I plan to have the nc symbol with attributes: > device=3DDRC_Directive > value=3DNoConnection > this way the backend can check for the directives of a net, so routing > style, differential pairs and so on can be added as well. You can look > at the drc2 backend for an example. > Of course, gsch2pcb and pcb have to support them if you want to use > this. > > Regards, > > Carlos > > El s=C3=A1b, 22-04-2006 a las 23:03 -0400, Dan McMahill escribi=C3=B3: > > Hello, > >=20 > > I noticed a commit message for adding 'directives' to gnetlist. I=20 > > wonder if this mechanism could be used to specify routing style to use=20 > > for different nets when using the PCB autorouter. > >=20 > > Or can one just add an attribute to a net to specify this? > >=20 > > -Dan > >
