Charlene, Thanks for sending the model files so that I could help answer your questions. I created a simple point-to-point net in ICX and simulated with the two models in question. Since the PPC file doesn't have a PCI model I assume you are using the PCI-X model. That should be OK, but be aware that PCI-X allows faster rise and fall times than standard PCI and this model switches pretty fast (6V/ns in the model waveforms, not into the specification load). On the Virtex side the PCI33 model has C_comp of 6pF which seems a bit on the high side for a modern part, but I think it's within the PCI specification.=20 I am suspicious of the PPC dynamic clamp in the PCI-X model. Essentially, what it does is double the power and ground clamp strength when the buffer is receiving. Does the datasheet of the part say that this is the intended operation? Here are a couple of things to experiment with to see how they affect your circuit: - adjust the C_comp value in the receiver model. Make it very small (1pF) and very large (20pF) to see what it does to both the receiver and driver waveforms. The reflections from the die capacitance do some interesting things back at the driver. - make the net much longer to separate out the reflections and study them. Make the net longer again to see if the reflection moves where you think it should. - Widen the traces so that the trace impedance is 40, 30, or 20 Ohms. See how that decreases the overshoot. The buffers are not well matched to the desired 60 Ohms for PCI. In summary, ICX is simulating the given models correctly and the overshoot is controlled by the power and ground clamps of the driver and receiver. As stated by others, PCI is rather noisy and the specification allows for this and expects buffers to have clamps to control it. If you have further questions about operation of ICX you can get great support at=20 http://supportnet.mentor.com. Regards, Weston -----Original Message----- From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx] On Behalf Of Beal, Weston Sent: Wednesday, July 09, 2008 1:01 PM To: crr1231@xxxxxxx; si-list@xxxxxxxxxxxxx Subject: [SI-LIST] Re: Virtex -5 PCI ibis file and simulation Charlene, Another route to get some help on this is to get Mentor Graphics customer support involved. We are familiar with ICX, IBIS and PCI. If you can send me the design and the IBIS files, or just the IBIS files, I can tell you if ICX is working properly, or if the models have problems, or hopefully explain the results you see in ICX. Regards, Weston weston_beal@xxxxxxxxxx -----Original Message----- From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx] On Behalf Of crr1231@xxxxxxx Sent: Tuesday, July 08, 2008 5:23 PM To: Aubrey_Sparkman@xxxxxxxx; si-list@xxxxxxxxxxxxx Subject: [SI-LIST] Re: Virtex -5 PCI ibis file and simulation I am using PCI (33MHz). The simulator says that my problem is with undershoot but I'm thinking that the model isn't very good. It is a point to point trace and very short (PPC to V5). I don't have room on the board for series resistors and don't realy want to go down that path. I'm dissapointed that the simulator (ICX) and the ibs model for the V5 is showing what it does. The only way I can reduce the undershoot is to insert the V5 with a fast-6mA driver in place of the PPC IO. Any other suggestions are welcomed. Thanks, Charlene -----Original Message----- From: Aubrey_Sparkman@xxxxxxxx To: weirsi@xxxxxxxxxx; crr1231@xxxxxxx Cc: si-list@xxxxxxxxxxxxx; cradtke@xxxxxxxxxxxxxxx Sent: Tue, 8 Jul 2008 1:13 pm Subject: [SI-LIST] Re: Virtex -5 PCI ibis file and simulation Charlene, You didn't say whether you were using PCI or PCI-X, but my memory says both PCI and PCI-X specs allowed HUGE amounts of over and undershoot. PCI-66 was often the worst case. Are you sure you violate the *shoot specs? The spec allows so much, I've only ever seen this once. Steve is right that series resistors can reduce the *shoots but that takes a lot of resistors and they can kill your setup time if you have a long link or several loads. Aubrey Sparkman=3D3D20 Enterprise Engineering Signal Integrity Team=3D3D20 Dell, Inc.=3D3D20 Aubrey_Sparkman@xxxxxxxx=3D3D20 (512) 723-3592=3D3D20 "The single biggest problem in communication is the illusion that it has taken place." -- George Bernard Shaw -----Original Message----- From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx] On Behalf Of steve weir Sent: Tuesday, July 08, 2008 2:42 PM To: crr1231@xxxxxxx Cc: si-list@xxxxxxxxxxxxx; cradtke@xxxxxxxxxxxxxxx Subject: [SI-LIST] Re: Virtex -5 PCI ibis file and simulation PCI is so old that this could be a real problem. I don't believe Xilinx does anything to particularly slow down V5 outputs when set for PCI I/O. External resistors should take care of the problem. Steve. crr1231@xxxxxxx wrote: > I was wondering if anyone else in the community has been able to implement (in simulation and in Hardware) PCI at 3.3v on the virtex 5 device (point to point between processer and FPGA). It seems that the V5 model that I am using responds the same whether I use 3.3V or 3.0V and gives the same over and undershoot regardless of trace length using the PCI models in the ibis file. According to my questionable simulations, overshoot is within range but undershoot is out by 300mV. My concern is that the sim is somewhat accurate, in hardware - the input diodes will not be able to clamp and the device will be damaged (over time). If anyone has successfully used an ibis model ( I am using the 1136 package), would you mind emailing it to me? > With much appreciation, > Charlene > > > ------------------------------------------------------------------ > To unsubscribe from si-list: > si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the Subject field > > or to administer your membership from a web page, go to: > //www.freelists.org/webpage/si-list > > For help: > si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field > > > List technical documents are available at: > http://www.si-list.net > > List archives are viewable at: =3D3D20 > //www.freelists.org/archives/si-list > or at our remote archives: > http://groups.yahoo.com/group/si-list/messages > Old (prior to June 6, 2001) list archives are viewable at: > http://www.qsl.net/wb6tpu > =3D3D20 > > > =3D3D20 -- Steve Weir Teraspeed Consulting Group LLC 121 North River Drive Narragansett, RI 02882=3D3D20 California office (866) 675-4630 Business (707) 780-1951 Fax Main office (401) 284-1827 Business (401) 284-1840 Fax=3D3D20 Oregon office (503) 430-1065 Business (503) 430-1285 Fax http://www.teraspeed.com This e-mail contains proprietary and confidential intellectual property of Teraspeed Consulting Group LLC ------------------------------------------------------------------------ ------------------------------ Teraspeed(R) is the registered service mark of Teraspeed Consulting Group LLC ------------------------------------------------------------------ To unsubscribe from si-list: si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the Subject field or to administer your membership from a web page, go to: //www.freelists.org/webpage/si-list For help: si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field List technical documents are available at: http://www.si-list.net List archives are viewable at: =3D3D20 //www.freelists.org/archives/si-list or at our remote archives: http://groups.yahoo.com/group/si-list/messages Old (prior to June 6, 2001) list archives are viewable at: http://www.qsl.net/wb6tpu =3D3D20 ------------------------------------------------------------------ To unsubscribe from si-list: si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the Subject field or to administer your membership from a web page, go to: //www.freelists.org/webpage/si-list For help: si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field List technical documents are available at: http://www.si-list.net List archives are viewable at: =3D20 //www.freelists.org/archives/si-list or at our remote archives: http://groups.yahoo.com/group/si-list/messages Old (prior to June 6, 2001) list archives are viewable at: http://www.qsl.net/wb6tpu =3D20 ------------------------------------------------------------------ To unsubscribe from si-list: si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the Subject field or to administer your membership from a web page, go to: //www.freelists.org/webpage/si-list For help: si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field List technical documents are available at: http://www.si-list.net List archives are viewable at: =3D20 //www.freelists.org/archives/si-list or at our remote archives: http://groups.yahoo.com/group/si-list/messages Old (prior to June 6, 2001) list archives are viewable at: http://www.qsl.net/wb6tpu =3D20 -- Binary/unsupported file stripped by Ecartis -- -- Type: image/jpeg -- File: SupportNet_light.jpg -- Desc: SupportNet_light.jpg ------------------------------------------------------------------ To unsubscribe from si-list: si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the Subject field or to administer your membership from a web page, go to: //www.freelists.org/webpage/si-list For help: si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field List technical documents are available at: http://www.si-list.net List archives are viewable at: =20 //www.freelists.org/archives/si-list or at our remote archives: http://groups.yahoo.com/group/si-list/messages Old (prior to June 6, 2001) list archives are viewable at: http://www.qsl.net/wb6tpu =20 ------------------------------------------------------------------ To unsubscribe from si-list: si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the Subject field or to administer your membership from a web page, go to: //www.freelists.org/webpage/si-list For help: si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field List technical documents are available at: http://www.si-list.net List archives are viewable at: //www.freelists.org/archives/si-list or at our remote archives: http://groups.yahoo.com/group/si-list/messages Old (prior to June 6, 2001) list archives are viewable at: http://www.qsl.net/wb6tpu