RE: pci compliant devices?

["Dalmau, John" <John.Dalmau@CAX.USA.XEROX.COM>]

My two cents worth on this. Yes the propagation delay for a 33MHz PCI bus
must be less then 30ns but for a device driver to be PCI compliant they must
meet more then the maximum propagation delay. The I/O drivers must meet
certain characteristics specified in the specification. Characteristics
include impedance values, rise and fall times, max and min sink and source
currents, and a slew of other things (see spec). For example, PCI relies on
reflective wave switching and therefore the output pad does not drive the
full rail voltage. Im 'ify' on this but I think it only drives 2.5Volts for
either 3V or 5V PCI.  Also, the 30ns period (for 33Mhz PCI) is budgeted into
three distinct portions not just propagation delay. 1) Source clock to out
2) actual propagation delay through the board (the bulk of the budget) 3)
setup time on the receiving end. In short, a device can not take 30ns to
drive a signal, to adhere to the spec the value is much much smaller. I dont
have the spec with me but I think its in the single digit ns range. 

Enjoy,

John Dalmau
Manager, Regional Design & Support Center
Xerox Corporation
701 South Aviation Blvd.
MS: ESAE-180
El Segundo, CA. 90245
www.xerox.com <http://www.xerox.com> 
 
(310) 333-5515 / 8*823-5515

As always standard "get off the hook" clause applies: This is my opinion
only and in no way shape or form does it reflect my company's view. 

-----Original Message-----
From: Meng-Hsi Chiu [mailto:d8342012@ccunix.ccu.edu.tw]
Sent: Thursday, March 09, 2000 7:33 AM
To: srisundar@dacafe.com
Cc: pci-sig@znyx.com
Subject: Re: pci compliant devices?


Because the clock rate for PCI bus is 33MHz, the propagation delay for

PCI agent must less than 30ns.

This is the meaning of PCI compliant.

srisundar@dacafe.com wrote:

> hi
>
> The FPGA vendors, EPLD vendors say, their devices are
> PCI compliant. What do they mean? What is this compliance to PCI?
>
> TIA
> Sri
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Dalmau, John.vcf