2. PCI Interface
32
PowerSpan II User Manual
80A1010_MA001_09
Integrated Device Technology
www.idt.com
There are two settings available for the Dual PCI PowerSpan II: Primary PCI Interface and Secondary
PCI Interface. The Primary PCI Interface adds extra functionality to the PCI Interface that is designated
as the Primary PCI Interface. The Secondary PCI Interface has no extra functionality.
The following features are associated with the Primary PCI Interface:
•
CompactPCI Hot Swap Support (see
“CompactPCI Hot Swap Silicon Support” on page 53
)
•
Vital Product Data (see
“Vital Product Data” on page 60
•
I
2
O Shell Interface (see
“I2O Shell Interface” on page 62
)
Either the PCI-1 Interface (64-bit) or the PCI-2 Interface (32-bit) can be configured as the Primary
Interface. The selected PCI interface is assigned as the Primary PCI Interface through the Primary PCI
Select (PWRUP_PRI_PCI) power-up option (see
“Resets, Clocks and Power-up Options” on page 167
for more information). Primary PCI functionality is shown in the value of the Primary PCI Bus
(PRI_PCI) bit in the
“Reset Control and Status Register” on page 324
. The PRI_PCI is a status bit and
only shows which bus is primary. It does not enable a bus as the Primary PCI Interface. The Primary
PCI interface is enabled with a power-up option (see
9. “Resets, Clocks and Power-up Options”
2.1.1.1
Clock Frequencies
Each of the PCI interfaces,
PCI-1 and PCI-2, run at frequencies from 25 MHz to 66 MHz. The DEV66
bit in the
“PCI-1 Control and Status Register.” on page 251
indicates that PowerSpan II is a 66
MHz-capable device.
The speed of these buses is determined through a power-up option (see
“Power-Up Options” on page 171
) using the corresponding P1_M66EN pins.
Both PCI interfaces run asynchronously to one another, and asynchronously to the Processor Bus
Interface.
2.1.2
PCI Data Width
The PCI-1 Interface is a 64-bit data interface that supports 32-bit addressing. The PCI-2 Interface is a
32-bit data interface that supports 32-bit addressing.
2.1.2.1
PowerSpan II in non-Hot Swap and PCI Host Applications
The PCI-1 Interface can be programmed to assert P1_REQ64# to indicate the data width of the PCI-1
bus at reset. This feature is controlled by the PWRUP_P1_R64_EN power-up option (see
) and minimizes required external logic. A logic low applied to P1_64EN#
enables this feature. PowerSpan II drives P1_REQ64# when PWRUP_P1_R64_EN is selected and
P1_64EN# is set to 0.
The Primary PCI Bus (PRI_PCI) bit in the
“Reset Control and Status Register” on page 324
always 0 in the Single PCI PowerSpan II.