GD82541PI Datasheet, PDF (12/46 Pages) Intel Corporation – 82541 Family of Gigabit Ethernet Controllers

82541(PI/GI/EI) — Networking Silicon
3.2.1
PCI Address, Data and Control Signals (44)
Symbol Type
Name and Function
AD[31:0] TS
C/BE#[3:0] TS
PAR
TS
FRAME# STS
IRDY#
STS
TRDY#
STS
STOP#
STS
Address and Data. Address and data signals are multiplexed on the same PCI pins. A
bus transaction includes an address phase followed by one or more data phases.
The address phase is the clock cycle when the Frame signal (FRAME#) is asserted
low. During the address phase AD[31:0] contain a physical address (32 bits). For I/O,
this is a byte address, and for configuration and memory, a DWORD address. The
82541(PI/GI/EI) device uses little endian byte ordering.
During data phases, AD[7:0] contain the least significant byte (LSB) and AD[31:24]
contain the most significant byte (MSB).
Bus Command and Byte Enables. Bus command and byte enable signals are
multiplexed on the same PCI pins. During the address phase of a transaction, C/
BE#[3:0] define the bus command. In the data phase, C/BE#[3:0] are used as byte
enables. The byte enables are valid for the entire data phase and determine which byte
lanes contain meaningful data.
C/BE[0]# applies to byte 0 (LSB) and C/BE#[3] applies to byte 3 (MSB).
Parity. The Parity signal is issued to implement even parity across AD[31:0] and C/
BE#[3:0]. PAR is stable and valid one clock after the address phase. During data
phases, PAR is stable and valid one clock after either IRDY# is asserted on a write
transaction or TRDY# is asserted after a read transaction. Once PAR is valid, it remains
valid until one clock after the completion of the current data phase.
When the 82541(PI/GI/EI) controller is a bus master, it drives PAR for address and write
data phases, and as a slave device, drives PAR for read data phases.
Cycle Frame. The Frame signal is driven by the 82541(PI/GI/EI) device to indicate the
beginning and length of a bus transaction.
While FRAME# is asserted, data transfers continue. FRAME# is de-asserted when the
transaction is in the final data phase.
Initiator Ready. Initiator Ready indicates the ability of the 82541(PI/GI/EI) controller
(as a bus master device) to complete the current data phase of the transaction. IRDY#
is used in conjunction with the Target Ready signal (TRDY#). The data phase is
completed on any clock when both IRDY# and TRDY# are asserted.
During the write cycle, IRDY# indicates that valid data is present on AD[31:0]. For a
read cycle, it indicates the master is ready to accept data. Wait cycles are inserted until
both IRDY# and TRDY# are asserted together. The 82541(PI/GI/EI) controller drives
IRDY# when acting as a master and samples it when acting as a slave.
Target Ready. The Target Ready signal indicates the ability of the 82541(PI/GI/EI)
controller (as a selected device) to complete the current data phase of the transaction.
TRDY# is used in conjunction with the Initiator Ready signal (IRDY#). A data phase is
completed on any clock when both TRDY# and IRDY# are sampled asserted.
During a read cycle, TRDY# indicates that valid data is present on AD[31:0]. For a write
cycle, it indicates the target is ready to accept data. Wait cycles are inserted until both
IRDY# and TRDY# are asserted together. The 82541(PI/GI/EI) device drives TRDY#
when acting as a slave and samples it when acting as a master.
Stop. The Stop signal indicates the current target is requesting the master to stop the
current transaction. As a slave, the 82541(PI/GI/EI) controller drives STOP# to request
the bus master to stop the transaction. As a master, the 82541(PI/GI/EI) controller
receives STOP# from the slave to stop the current transaction.
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