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Datasheet
17
Networkin
g
Silicon — GD82559ER
Write Accesses:
The CPU, as the initiator, drives the address lines
AD[31:0],
the command and
byte enable lines
C/BE#[3:0] and
the control lines
IRDY#
and
FRAME#
. It also provides the
82559ER with valid data immediately after asserting
IRDY#
. The 82559ER controls the
TRDY#
signal and de-asserts it for a certain number of clocks until valid data is written to the Flash buffer.
By asserting
TRDY#
, the 82559ER signals the CPU that the current data access has completed.
Flash buffer write accesses can be byte length only.
4.2.1.1.3 Retr
y
Premature Accesses
The 82559ER responds with a Retry to any configuration cycle accessing the 82559ER before the
completion of the automatic read of the EEPROM. The 82559ER may continue to Retry any
configuration accesses until the EEPROM read is complete. The 82559ER does not enforce the
rule that the retried master must attempt to access the same address again to complete any delayed
transaction. Any master access to the 82559ER after the completion of the EEPROM read will be
honored. Figure 6 depicts the operation of a Retry cycle.
Fi
g
ure 5. Flash Buffer Write C
y
cle
SYSTEM
82559ER
CLK
FRAME#
C/BE#
IRDY#
TRDY#
DEVSEL#
AD
ADDR
MEM WR BE#
STOP#
DATA