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3–10 User Guide Version 11.1 Altera Corporation

PCI Compiler October 2011

Functional Overview

When the pci_mt64 or pci_mt32 function is ready to present or accept

data on the bus, it asserts irdyn. At this point, the PCI master logic

monitors the control signals driven by the target device. The target device

decodes the address and command signals presented on the PCI bus

during the address phase of the transaction and drives the control signals

devseln, trdyn, and stopn to indicate one of the following conditions:

■ The data transaction has been decoded and accepted

■ The target device is ready for the data operation. When both trdyn

and irdyn are active, a data word is clocked from the sending to the

receiving device

■ The master device should retry the current transaction

■ The master device should stop the current transaction

■ The master device should abort the current transaction

Table 3–1 shows the possible control signal combinations on the PCI bus

during a transaction. The PCI function signals that it is ready to present

or accept data on the bus by asserting irdyn. At this point, the

pci_mt64 master logic monitors the control signals driven by the target

device and asserts its control signals appropriately. The local-side

application can use the lm_tsr[9..0] signals to monitor the progress

of the transaction. The master transaction can be terminated normally or

abnormally. The local side signals a normal transaction termination by

asserting the lm_lastn signal. The abnormal termination can be caused

by either a target abort, master abort, or latency timer expiration. Refer to

“Abnormal Master Transaction Termination” on page 3–125 for more

details.

In addition to single-cycle and burst 32-bit transactions, the local side

master can request 64-bit transactions by asserting the lm_req64n

signal. In 64-bit transactions, the pci_mt64 function behaves the same as

a 32-bit transaction except for asserting the req64n signal with the same

timing as the framen signal. Additionally, the pci_mt64 function treats

the local side as 64 bits when it requests 64-bit transactions and when the

target device accepts 64-bit transactions by asserting the ack64n signal.

Refer to “Master Mode Operation” on page 3–134 for more information

on 64-bit master transactions.

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Altera PCI Compiler Manual do Utilizador Página 84