yy7d6 said:
PeteS,
8-inches, then 66Mhz should have longer maximum trace length.
Is that the "PCI-X Addendum to the PCI Local Bus" Specification you are
saying?
BTW, are you familiar with Single board computers(SBC) with one
PCI/PCI-x edge connector (i.e for the connection of SBC to Backplane);
the length of the overall trace of the PCI is SBC board pci
traces+backplane traces right?,
What bothers me is that i know the routing guidelines for Add-In card
but does that also apply for PCI on motherboard or SBCs?
What revision of the specification do you have? In my copy it says for
the PCI 32-bit signals 1.5", for the 64-bit extenstion 2.5"; can you
site the information about the 8" (because i'm really having problems
keeping up with the length limit).
Ayon kay PeteS:
The PCI spec can be very confusing.
Lengths are specified two ways:
Motherboard is specified in terms of propagation delay
Add-in cards are specified in terms of length on FR4
The add-in card lengths are the minimums for the entire system,
incidentally.
Be careful of the signals on 64 bit - the original 32 bit signals still
require the standard lengths. In addition, make sure that REQ64 has a
*longer* prop delay than reset to make sure it is valid during the
rising edge of reset. If you give them the same prop delays, you can
always use a higher value pullup to 'slow' the rising edge, but make
sure you avoid the potential race condition.
Cheers
PeteS
