Computer Hardware User Manual

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System Implementation

1-9

PCI445X Device

IDSEL, there is no alternative. If another AD line is to be used for IDSEL,

then the system designer must leave the pullup off LATCH and use

MFUNC7 to route IDSEL. Also, if AD23 is used, then the resistive coupling

should not be used.

Refer to the

Implementation Note: System Generation of IDSEL

in the

PCI

Local Bus Specification, Revision 2.2 (section 3.2.2.3.5)

PCI Local Bus

Specification, Revision 2.2 (section 4.2.6, footnote 31)

recommends

resistive coupling. A 100-Ω resistor is recommended.

 PRST (PCI reset) and G_RST (Global reset)

G_RST initializes all of the registers and state-machines of the PCI445X

device, and PRST does not. G_RST should be asserted during power-on

and rebooting. It puts the PCI445X device into the initialized state. PRST

does not initialize global-reset-only bits and, if PME is enabled, PME

context bits. Refer to Table A–1, Global Reset Only Cleared Bits, and

Table A–2, PME Context Bits

. PRST is connected to PCI RESET; G_RST

requires a special signal in the motherboard. It will come from the chipset.

If the system does not support wake-up from D3

cold,

then PRST and

G_RST can be tied together. Note that G_RST and PRST are clamped to

CCP.



INTA, INTB, and INTC

When using one of the parallel PCI interrupt modes, INTA, INTB, and INTC

should be connected to the PCI interrupt lines. If the INTRTIE bit (system

control register, PCI offset 80h, bit 29) is set, then both CardBus functions

(functions 0 and 1) will signal and report INTA

, and only INTA and INTC will

need to be routed. If the TIEALL bit (system control register, PCI offset

80h, bit 28) is set, then all functions (0, 1, and 2) will report INTA and INTA

will be the only interrupt required.

 CLKRUN

This signal is optional. However, if saving power is a concern, this signal

should be implemented. Refer to the

PCI Mobile Design Guide

Revision 1.1 (Section 2)

 PME

This signal is required for the ACPI systems. In a notebook PC, this signal

is usually connected to the south bridge (ex., PIIX4) or embedded

controller (EC). The PME

terminal uses an open-drain type buffer.

Note: Pullup Resistor Requirements

A pullup resistor is required for each of the following terminals: IRDY, TRDY,

FRAME, STOP, DEVSEL, PERR, SERR, LOCK, PRST, G_RST, INTA, INTB,

INTC, CLKRUN, and PME.