Content-Type: text/plain; charset="gb2312" Content-Transfer-Encoding: quoted-printable =20 1, If a typical figure for PCB propagation delay of 150ps per = inch is used and PCI clock is 33MHz , the trace length of data signal is = shorter than 5/0.15 =3D33.33 inch , is it right ? 2. how many inchs is the clock trace length longer than the = data signal trace length ? 3. In our PCB : =20 PCIdevice =20 PCI device =20 Motorola 8245 =20 10/100PCI device =20 10/100 PCI device =20 =20 =20 =20 ! ! = ! ! = ! PCI BUS =20 = =A3=A1=A1=AA=A1=AA=A1=AA=A1=AA=A1=AA=A1=AA=A1=AA=A1=AA=A1=AA=A1=AA=A1=AA=A1= =AA=A1=AA=A1=AA=A1=AA=A1=AA=A1=AA=A1=AA signal length 30 inch = =A1=AA=A1=AA=A1=AA=A1=AA=A1=AA=A1=AA=A1=AA=A1=AA=A1=AA=A1=AA=A1=AA=A1=AA=A1= =AA=A1=AA=A1=AA=A1=AA=A1=AA=A1=AA=A1=AA =A3=A1 =20 The clock length is 40inch and it is equal to each device=20 =20 It can work ? ? ? =20 =20 =20 -----=D3=CA=BC=FE=D4=AD=BC=FE----- =B7=A2=BC=FE=C8=CB: steve weir [mailto:weirsp@xxxxxxxxxx]=20 =B7=A2=CB=CD=CA=B1=BC=E4: 2004=C4=EA4=D4=C211=C8=D5 19:12 =CA=D5=BC=FE=C8=CB: si-list@xxxxxxxxxxxxx =D6=F7=CC=E2: Re: [SI-LIST] about PCI clock length =20 Myan, 1. PCI 66 MHz allows 5ns for propagation and settling, PCI 33 MHz allows = 10ns. These are the real limitations that you need to be aware of. = Because PCI is not really terminated properly, the configuration of the = drivers and the loads, and their locations will determine what you can = actually get away with. 2. PCI 66 MHz allows 1ns skew. A one inch difference is only about = 1/5th of that. =20 3. See (1). PCI performs best when there are only driving devices at = the far ends of the bus. The more loads you place in the middle, the = more your margins will erode. All of that being said, there are plenty = of PC's that run just fine with five PCI slots. Steve. At 05:18 PM 4/11/2004 +0800, myan@xxxxxxxxxxxxxx wrote: I have some questions : 1. how long is the limit length of PCI clock trace length on PCB ?=20 2. Is there any skew between the PCI clock and data signals besides that = PCI clock is 2.5inch and data signals is shorter than 1.5 inch on = daughter card ? 3. is ther any problem that the PCI host is in the middle of the PCI bus = and there are two PCI devices on the both sides of the PCI host=20 =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 FAQ wiki page is located at: http://si-list.org/wiki/wiki.pl?Si-List_FAQ List technical documents are available at: http://www.si-list.org <http://www.si-list.org/>=20 List archives are viewable at: =20 <//www.freelists.org/archives/si-list> = //www.freelists.org/archives/si-list or at our remote archives: <http://groups.yahoo.com/group/si-list/messages> = http://groups.yahoo.com/group/si-list/messages Old (prior to June 6, 2001) list archives are viewable at: <http://www.qsl.net/wb6tpu> http://www.qsl.net/wb6tpu =20 Steve Weir Teraspeed Consulting Group LLC=20 2926 SE Yamhill St.=20 Portland, OR 97214=20 (503) 239-5536=20 http://www.teraspeed.com <http://www.teraspeed.com/>=20 -------------------------------------------------------------------------= ----------------------------- Teraspeed(SM) is the service mark of Teraspeed Consulting Group LLC -- Binary/unsupported file stripped by Ecartis -- -- Type: image/gif -- File: image001.gif -- Desc: image001.gif ------------------------------------------------------------------ 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 FAQ wiki page is located at: http://si-list.org/wiki/wiki.pl?Si-List_FAQ List technical documents are available at: http://www.si-list.org 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