Interfacing via ISA bus is very easy but slow and it is getting difficult to
find ISA based PCs.
USB bus easy to use but its packet stucture and therefore the latency is an
issue for some real-time applications.
So, I want to learn how to build and work/play with PCI interfaces. Can you
suggest what is the easiest and low-cost way of involving with the PCI bus
to learn with hands on experiments?
Try PLX Technology, www.plxtech.com. They make PCI bus interface chips
and they have eval boards and reference design kits for their parts.
I have used their parts on several projects and been very satisfied.
This is the reason I keep ISA bus based PCs around and working.
Well, ponying up to PCI will not be cheap. First, you need to understand the
difference between reflection wave and incident wave -- PCI is reflection wave.
Second, there are very tight constraints implied by the technology. Your PCI
clock line must be 1.5" +/- 0.1" in length, signal lines are to be less than
2.5" (if memory serves), and you will often find weird serpentine clock lines to
meet that 1.5" requirement. Third, because of the loading requirements (at
33MHz, some 10pF total; at 66Mhz, 5pF), you will be using an ASIC. No discrete
logic with multiple loads on single lines, for example. Fourth, you will pay
much more dearly for instruments that can monitor and display PCI bus signals.
Fifth, PCI mandates plug-and-play and certain minimum register requirements and
the ability to assign block addresses, if needed.
You can get low cost ASICs. But the rest makes this not low-cost and there is a
high threshold of knowledge required, as well. PCI was almost designed from the
ground up to exclude basement developers.
Most modern PCB design packages will tell you the length of a trace.
No real problem here.
ASIC? FPGA will do just fine, but the chips made by PLX are often
found as a universal piece of glue.
??? The 96 channel / 100MHz logic analyzer I picked up on Ebay for US$
66 works very nice to monitor PCI signals.
Creating a PCI implementation is difficult, but there are numerous
ways to get a PCI core or bridge (like the PLX chips). No need to
bother with tedious timing.
The PCI specification can be downloaded from several sites. It just
comes down to a proper PCB layout on the PCI side.
The fastest way to get started with PCI is using a PLX chip.
Reply to nico@nctdevpuntnl (punt=.)
Bedrijven en winkels vindt U op www.adresboekje.nl
We wrote a little DOS app that makes PCI bios calls. It can find a PCI
board and drag it down into a hole in the 640K-1M real address space
where you can bang the registers all you want. Works under DOS or
I wonder if there are any equivalent true-Windows programs.
You might want to take a look at this:
I've made this card exactly for this application: to allow myself to
interface to a modern PC without fighting with the PCI bus every time. It is
basically a simple ISA-like PCI bridge. You can attach a douther-card on top
of it and add whaterver circuit you like. You don't even need a driver if
you can go without interrupts.
AFAIK the PLX chips have a rather straight-forward backend bus, and I think some
of them can even do PCI to ISA if you really want to, so apart from the
you need to have a decent PCB if you want it to work reliably it shouldn't
be that difficult and PLX most likely have an app-note on how the PCB should
On Wed, 02 Feb 2005 23:43:25 +0100, Lasse Langwadt Christensen
There is still a high learning curve if something does NOT work as you expect it
to. You need the tools and the knowledge.
Of course, if everything works right out of the box, so to speak, then no
problem. But then reality does impinge.
I still do NOT consider PCI development to be hobbyist stuff.
On Wed, 02 Feb 2005 19:00:33 +0000, Jonathan Kirwan wrote:
You really don't have to get into it in that detail unless you're pushing
2.5" +- /1", though that isn't generally a problem. For a product, sure.
Must be less than .75", IIRC. They really need to be as short as
possible. 2.5" likely *won't* work. Stubs are badness!
Yes, almost always (2.5").
Yes, and the receivers aren't typical CMOS. Many FPGAs have PCI I/O.
Either is a bad plan for one-off designs though. As mentioned before in
this thread, PLX bridges are the way to go. They have PCI<->ISA brifges
that work quite well. There are also PCI<->ISA cards.
Not really true. There are some relatively cheap bus monitors. If one
sticks to a known bridge design a scope is all that's needed. I got a
PLX-9054 based card running with no more than a scope.
Another reason to go with a known design. ;-)
Not ASICs. ASSPs (Application Specific Standard Products).
Designed to exclude? Are you implying that they intentionally raised the
entry bar? That's some charge! There is a reason for complication. It
makes life simpler. ;-)
Generic cards are hard to come by and probably wouldn't work. There can only
be one PCI-to-ISA bridge in a system and that's usually in the chipset
(nowdays it is the bridge towards the LPC bus). PLX has a board with the
PCI9052 that has an ISA bus slot on it (the PCI 9052RDK-LITE for $299) but
that's far from being a universal solution.
On 3 Feb 2005 15:12:33 -0800, firstname.lastname@example.org wrote:
The southbridge or PCI-ISA bridge chip can only exist with "side-band" channels
to the main chipset. There is only one of these possible, and then only if the
rest of the chipset supports the southbridge concept. The side-band channels do
not exist as signals on the PCI bus, so I don't believe that it would be
possible to do a PCI board that provides full ISA -- more particularly, support
for ISA DMA. You might be able to get by with some specialized FPGA or ASIC for
the purposes of a reduced ISA feature set connecting to the PCI (no DMA and with
subtractive decoding for the ISA address space.)
I haven't heard of such a thing, though.
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