Re: [pci] 3.3V to 5V bus problem

[Stefan Bergström <stb@viking2001.se>]

Hi Marco

I'm running my PCI board in standard Intel and AMD PCs. The Altera chip
I'm using EP20K400EBC is not 3.3V tolerant but it's working anyway. That
is because a modern PC only drives 3.3V. Older motherboards drive the
signals to 5V. Make sure you test this before you plug in your board.

Some old PCI boards, such as Sound boards, Network Interface cards may
drive signals to 5V.

Some older motherboard does not supply 3.3V power to the PCI bus. It is
not necessary according to the PCI standard. All new motherboards do
have 3.3V power supply.

When I say old PCs I'm talking about several years. You should not
encounter them often.

I do not recommend you to sell a board with this limitation to 'ordinary
users'. My board is only used in industrially environment in our own
PCs. No unauthorized hardware is installed in those.

Have Fun
STB

-----Ursprungligt meddelande-----
Från: owner-pci@opencores.org [mailto:owner-pci@opencores.org] För Marco
Buffa
Skickat: den 4 december 2002 11:41
Till: pci@opencores.org
Ämne: [pci] 3.3V to 5V bus problem

Hi,
I have a trivial problem designing a PCI board with the PCI bridge 
implemented on a Xilinx Spartan IIE.

The problem is that this FPGA (3.3V) is not 5V tolerant, but I suppose 
the PCI bus signals are 5V scaled. (Is it correct? I can't find any 3.3V

PCI bus connector, with the correct keyways, on my mother-board)

Did someone know the solution?

Thank's.
-- 
Marco (Politecnico di Milano, Italy)

"No, lo abbiamo esaminato dopo, e' perfetto.
Ma quando si ha paura si crede sempre che il motore vibri."
(Antoine de Saint-Exupery, "Volo di notte")

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