PI7C8154BNAE Pericom Semiconductor, PI7C8154BNAE Datasheet - Page 27

• Manufacturer Part Number: PI7C8154BNAE
• Description: IC PCI-PCI BRIDGE ASYNC 304-PBGA
• Manufacturer: Pericom Semiconductor

Specifications of PI7C8154BNAE

• Applications: *
• Interface: *
• Voltage - Supply: *
• Package / Case: 304-BGA
• Mounting Type: Surface Mount
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

2.6.4
2.6.5
PI7C8154B claims the access by asserting DEVSEL# and returns TRDY# to the initiator, to
indicate that the write data was transferred. If the initiator requests multiple DWORD, PI7C8154B
also asserts STOP# in conjunction with TRDY# to signal a target disconnect. Note that only those
bytes of write data with valid byte enable bits are compared. If any of the byte enable bits are
turned off (driven HIGH), the corresponding byte of write data is not compared.
If the initiator repeats the write transaction before the data has been transferred to the target,
PI7C8154B returns a target retry to the initiator. PI7C8154B continues to return a target retry to the
initiator until write data is delivered to the target, or until an error condition is encountered. When
the write transaction is repeated, PI7C8154B does not make a new entry into the delayed
transaction queue. Section 2.11.3.1 provides detailed information about how PI7C8154B responds
to target termination during delayed write transactions.
PI7C8154B implements a discard timer that starts counting when the delayed write completion is at
the head of the delayed transaction completion queue. The initial value of this timer can be set to
the retry counter register offset 78h.
If the initiator does not repeat the delayed write transaction before the discard timer expires,
PI7C8154B discards the delayed write completion from the delayed transaction completion queue.
PI7C8154B also conditionally asserts P_SERR# (see Section 5.4).
WRITE TRANSACTION ADDRESS BOUNDARIES
PI7C8154B imposes internal address boundaries when accepting write data. The aligned address
boundaries are used to prevent PI7C8154B from continuing a transaction over a device address
boundary and to provide an upper limit on maximum latency. PI7C78154 returns a target
disconnect to the initiator when it reaches the aligned address boundaries under conditions shown
in Table 2-3.
Table 2-3 WRITE TRANSACTION DISCONNECT ADDRESS BOUNDARIES
Note 1. Memory write disconnect control bit is bit 1 of the chip control register at offset 40h in the configuration space.
BUFFERING MULTIPLE WRITE TRANSACTIONS
PI7C8154B continues to accept posted memory write transactions as long as space for at least one
DWORD of data in the posted write data buffer remains. If the posted write data buffer fills before
the initiator terminates the write transaction, PI7C8154B returns a target disconnect to the initiator.
Type of Transaction
Delayed Write
Posted Memory Write
Posted Memory Write
Posted Memory Write and
Invalidate
Posted Memory Write and
Invalidate
Posted Memory Write and
Invalidate
Condition
All
Memory write disconnect control
bit = 0
Memory write disconnect control
bit = 1
Cache line size ≠ 1, 2, 4, 8, 16
Cache line size = 1, 2, 4, 8
Cache line size = 16
(1)
(1)
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Aligned Address Boundary
Disconnects after one data transfer
4KB aligned address boundary
Disconnects at cache line boundary
4KB aligned address boundary
Cache line boundary if posted memory write data
FIFO does not have enough space for the next
cache line
16-DWORD aligned address boundary
ASYNCHRONOUS 2-PORT
JUNE 2008 REVISION 1.1
PCI-to-PCI BRIDGE
Advance Information
PI7C8154B