32581C

Signal Definitions

3.4.6PCI Bus Interface Signals (Continued)

Signal Name

BalL No.

Type

Description

Mux

 

 

 

 

 

REQ1#

A5

I

Request Lines. REQ[1:0]# indicate to the arbiter that an

---

 

 

 

agent requires the bus. Each master has its own REQ#

 

REQ0#

B5

 

---

 

line. REQ# priorities (in order) are:

 

 

 

 

 

 

 

1)

VIP

 

 

 

 

2)

IDE Channel 0

 

 

 

 

3)

IDE Channel 1

 

 

 

 

4)

Audio

 

 

 

 

5)

USB

 

 

 

 

6)

External REQ0#

 

 

 

 

7)

External REQ1#.

 

 

 

 

Each REQ# is internally connected to a pull-up resistor.

 

 

 

 

 

 

GNT1#

C6

O

Grant Lines. GNT[1:0]# indicate to the requesting mas-

DID1 (Strap)

 

 

 

ter that it has been granted access to the bus. Each mas-

 

GNT0#

C5

 

DID0 (Strap)

 

ter has its own GNT# line. GNT# can be retracted at any

 

 

 

 

 

 

 

time a higher REQ# is received or if the master does not

 

 

 

 

begin a cycle within a minimum period of time (16 PCI

 

 

 

 

clocks).

 

 

 

 

Each of these signals is internally connected to a pull-up

 

 

 

 

resistor.

 

 

 

 

GNT0# must have a pull-up resistor of 1.5 KΩ and

 

 

 

 

GNT1# must have a pull-up resistor of 1.5 KΩ.

 

 

 

 

 

 

 

56

AMD Geode™ SC3200 Processor Data Book

Page 56
Image 56
AMD SC3200 manual REQ1#, REQ0#, Vip, Usb, GNT1#, GNT0#