Altera PCI Compiler - Manual (Page 84)

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.