Altera PCI Compiler - Manual (Page 95)

Altera Corporation User Guide Version 11.1 3–21
October 2011
Functional Description
lt_rdyn Input Low Local target ready. The local side asserts lt_rdyn to indicate
a valid data input during target read, or ready to accept data
input during a target write. During a target read,
lt_rdyn
deassertion suspends the current transfer (i.e., a wait state is
inserted by the local side). During a target write, an inactive
lt_rdyn signal directs the PCI MegaCore function to insert
wait states on the PCI bus. The only time the function inserts
wait states during a burst is when
lt_rdyn inserts wait states
on the local side.
lt_rdyn is sampled one clock cycle before actual data is
transferred on the local side. During target write transactions,
lt_rdyn has also special functionality. To allow the local side
ample time to issue a retry for the write cycle, the PCI
MegaCore function does not assert
trdyn in the first data
phase unless the local side asserts lt_rdyn . In this case, the
local side asserts lt_rdyn to indicate that it intends to
complete at least one data phase and it is not going to issue a
retry.
Refer to the “Additional Design Guidelines for Target
Transactions” on page 3–88 section for additional information
about the lt_rdyn functionality.
lt_framen Output Low Local target frame request. The lt_framen output is
asserted while the PCI MegaCore function is requesting
access to the local side. It is asserted one clock cycle before
the function asserts
devseln , and it is released after the last
data phase of the transaction is transferred to/from the local
side.
lt_ackn Output Low Local target acknowledge. The PCI function asserts lt_ackn
to indicate valid data output during a target write, or ready to
accept data during a target read. During a target read, an
inactive
lt_ackn indicates that the function is not ready to
accept data and local logic should delay the bursting operation.
During a target write,
lt_ackn de-assertion suspends the
current transfer (i.e., a wait state is inserted by the PCI master).
The
lt_ackn signal is only inactive during a burst when the
PCI bus master inserts wait states.
lt_dxfrn Output Low Local target data transfer. The PCI MegaCore function asserts
the
lt_dxfrn signal when a data transfer on the local side is
successful during a target transaction.
Table 3–7. Target Signals Connecting to the Local Side (Part 2 of 3)
Name Type Polarity Description