3-6 Signal Descriptions
3.3.3 Interface Control Signals

Tabl e 3.4 describes the Interface Control signals.

Table 3.4 Interface Control Signals

Name PQFP BGA Type Strength Description
FRAME/ 16 F2 S/T/S 8mA PCI Cycle Frame is driven by the currentmaster to indicate
the beginning and duration of an access. FRAME/ is
assertedto indicate that a bus transaction is beginning.
While FRAME/ is deasserted, eitherthe transaction is
in the final data phase or thebus is idle.
TRDY/ 19 G3 S/T/S 8 mA PCI Target Ready indicates the target agent’s(selected
device’s)ability to complete the current data phase of
the transaction. TRDY/is used with IRDY/. A data
phase is completed on any clockwhen used with
IRDY/.A data phase is completed on any clock when
bothTRDY/ and IRDY/ are sampled asserted. During a
read, TRDY/indicates that valid data is present on
AD[31:0]. During a write, it indicatesthat the target is
prepared to acceptdata. Wait cycles are inserted until
both IRDY/and TRDY/ are asserted together.
IRDY/ 17 F1 S/T/S 8 mA PCI Initiator Ready indicatesthe initiating agent’s (bus
master’s)ability to complete the current data phase of
the transaction. IRDY/is used with TRDY/. A data
phaseis completed on any clock when both IRDY/ and
TRDY/are sampled asserted. During a write, IRDY/
indicatesthat valid data is present on AD[31:0]. During
a read, it indicates that themaster is prepared to
accept data. Waitcycles are inserted until both IRDY/
and TRDY/are asserted together.
STOP/ 22 G4 S/T/S 8 mA PCI Stop indicates that the selected target is requesting
the master to stop the current transaction.
DEVSEL/ 20 G2 S/T/S 8 mA PCI Device Select indicates that the dr iving device has
decoded its address as thetarget of the current
access. As an input,it indicates to a master whether
any deviceon the bus has been selected.
IDSEL 2 B1 I N/A InitializationDevice Select is used as a chip select in
place of the upper 24 address lines during
configuration read and write transactions.