2. PCI Interface
34
PowerSpan II User Manual
80A1010_MA001_09
Integrated Device Technology
www.idt.com
•
PCI bus is currently a 64-bit slot and the Hot Swap board is 64-bit capable. In this case,
P1_REQ64# could be anything but P1_64EN# is GND and the card will initialize in 64-bit mode.
•
PCI bus is currently a 64-bit slot and the Hot Swap board is 32-bit capable. In this case,
P1_REQ64# is not sampled and P1_64EN# does not exist on the board so initialization would be
32-bit mode.
2.1.2.4
PowerSpan II Drives PCI 64-bit Extension Signal in 32-bit Environment
When PowerSpan II's 64-bit PCI interface is programmed to operate in 32-bit mode, the 64-bit
extension PCI bus signals can be left open. PowerSpan II actively drives the following the input
signals:
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Driven Low
— P1_ADb[63:32]#
— P1_CBE[7:4]#
— P1_REQ64#
— P1_ACK64#
— P1_PAR64#
— P1_PAR64#
— P1_REQ64#
— P1_ACK64#
This insures the signals do not oscillate and that there is not a significant power drain through the input
buffer.
2.1.3
PCI Interface Descriptions
The PowerSpan II PCI interfaces are described in terms of its PCI master and PCI target functions. This
description is largely independent of PCI-1 versus PCI-2, or the assignment of the Primary PCI
Interface functions. Exceptions to these rules are noted as required.
2.1.4
Transaction Ordering
PowerSpan II implements a set of ordering rules for transactions initiated by master(s) connected to
PCI Interface Px, that are destined for targets and/or slaves connected to PCI Interface Py.
Cross-references to PCI registers are shown as PCI-1 whenever the
cross-references apply equally to PCI-1 or PCI-2 registers.
Transactions initiated by master(s) connected to PCI Interface Px, but with different
PowerSpan II destination interfaces, are independent from an ordering perspective.
Transactions initiated by PowerSpan II DMA and PowerSpan II generated interrupt events
have no ordering relationship to externally initiated transactions processed by PowerSpan II.