PI7C8150ND Pericom Semiconductor, PI7C8150ND Datasheet - Page 24

• Manufacturer Part Number: PI7C8150ND
• Manufacturer: Pericom Semiconductor

Specifications of PI7C8150ND

• Operating Temperature (min): 0C
• Operating Temperature Classification: Commercial
• Operating Temperature (max): 85C
• Package Type: BGA
• Rad Hardened: No
• Case: BGA
• Dc: 04+
• Lead Free Status / Rohs Status: Not Compliant

PI7C8150
2-PORT PCI-TO-PCI BRIDGE
ADVANCE INFORMATION
A delayed write transaction guarantees that the actual target response is returned back to
the initiator without holding the initiating bus in wait states.
A delayed write transaction is limited to a single DWORD data transfer.
When a write transaction is first detected on the initiator bus, and PI7C8150 forwards it as
a delayed transaction, PI7C8150 claims the access by asserting DEVSEL_L and returns a
target retry to the initiator. During the address phase, PI7C8150 samples the bus command,
address, and address parity one cycle later. After IRDY_L is asserted, PI7C8150 also
samples the first data DWORD, byte enable bits, and data parity. This information is
placed into the delayed transaction queue. The transaction is queued only if no other
existing delayed transactions have the same address and command, and if the delayed
transaction queue is not full. When the delayed write transaction moves to the head of the
delayed transaction queue and all ordering constraints with posted data are satisfied. The
PI7C8150 initiates the transaction on the target bus. PI7C8150 transfers the write data to
the target. If PI7C8150 receives a target retry in response to the write transaction on the
target bus, it continues to repeat the write transaction until the data transfer is completed, or
until an error condition is encountered.
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If PI7C8150 is unable to deliver write data after 2
(default) or 2
(maximum) attempts,
PI7C8150 will report a system error. PI7C8150 also asserts P_SERR_L if the primary
SERR_L enable bit is set in the command register. See Section 6.4 for information on the
assertion of P_SERR_L. When the initiator repeats the same write transaction (same
command, address, byte enable bits, and data), and the completed delayed transaction is at
the head of the queue, the PI7C8150 claims the access by asserting DEVSEL_L and returns
TRDY_L to the initiator, to indicate that the write data was transferred. If the initiator
requests multiple DWORD, PI7C8150 also asserts STOP_L in conjunction with TRDY_L
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, PI7C8150 returns a target retry to the initiator. PI7C8150 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, PI7C8150 does not make a new entry
into the delayed transaction queue. Section 3.8.3.1 provides detailed information about how
PI7C8150 responds to target termination during delayed write transactions.
PI7C8150 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, PI7C8150 discards the delayed write completion from the delayed
transaction completion queue. PI7C8150 also conditionally asserts P_SERR_L
(see Section 6.4).
3.5.4
WRITE TRANSACTION ADDRESS BOUNDARIES
PI7C8150 imposes internal address boundaries when accepting write data.
The aligned address boundaries are used to prevent PI7C8150 from continuing
a transaction over a device address boundary and to provide an upper limit on maximum
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March 19, 2003 – Revision 1.04