Chris, Go to http://www.connecteda.com/ I wrote an article for ELECTRA that may help you route your design. This is not an advertisement for Electra, I am just sharing my knowledge.
Mike Reagan EDSI Frederick MD ---------- Original Message ---------------------------------- From: Chris Fisher <[EMAIL PROTECTED]> Reply-To: "Protel EDA Forum" <[EMAIL PROTECTED]> Date: Fri, 13 Aug 2004 08:57:40 -0700 (PDT) > > >I have a large? project I am trying to route with DXP 2004. This is my >first project using DXP, although I have spent time with test designs and >tutorials. > >The big SMT parts of my design are four 34x34 BGAs @ 1mm spacing and 24 >160-pin 0.8mm spacing connectors. I am planning to escape two nets >between vias under the BGA. > >The first thing I found is that the auto fanout of the connectors was >rather poor. Also the autorouter did very poorly with escaping the >via-grid under the BGA. I then tried prerouting the fanouts and escapes >in the footprints. With careful layer assignment and fanout, each net >going between BGAs and connectors can be routed on one layer (between >fanout vias). > >At this point when I run the autorouter, it does a fairly poor jobs (lots >of vias and bad decisions that lead to contention & failures). > >Most FPGA boards I have seen use a layer topology that is radial, where >the FPGA is the center (at least in the area around the FPGA). The >closest match in DXP is the "Any" setting. This setting appears to assign >one of the fixed directions for the layer, instead of letting each net go >any direction on that layer. > >What I am hoping is that I can get the autoroute to connect (without >changing layers) all the nets between my BGAs and connectors. Can this be >done? > >This board also has a small number of 100 ohm differential pairs. At this >time the autorouter does not support differential pair routing, so I was >planning on hand-routing these signals. Is this what everyone else does? > >Questions: > >Has anyone else tried using the autorouter this way (partial prerouting >of nets)? >The autorouter seems to ignore the copper on partially pre-routed nets? >Is there a workaround to get it to start from a section of copper instead >of a pad? > >Is there a way to individually restrict the signal layers used for each >net? >Is there a way to restrict the autorouter to only use only one layer? > > >Is a radial layer direction possible to support with the autorouter? > > > > >Does anyone have any further ideas? > >Thanks, >Chris Fisher > > > > > > > > > * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * To post a message: mailto:[EMAIL PROTECTED] * * To leave this list visit: * http://www.techservinc.com/protelusers/leave.html * * Contact the list manager: * mailto:[EMAIL PROTECTED] * * Forum Guidelines Rules: * http://www.techservinc.com/protelusers/forumrules.html * * Browse or Search previous postings: * http://www.mail-archive.com/[EMAIL PROTECTED] * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
