Revision 1.02 – April 12, 2007
S5920 – PCI Product: PCI Bus Protocol
Data Book
Table 53. Target Termination Type
Termination
Disconnect
Retry
DEVSEL#
STOP#
on
TRDY#
on
Comment
on
on
off
Data is transferred. Transaction needs to be re-initiated to complete.
Data was not transferred. Transaction should be tried later.
Data was not transferred. Fatal error.
on
off
Abort
on
off
Targets selected with LOCK# deasserted during the
assertion of FRAME# (clock period 1 of Figure 6),
which encounter the assertion of LOCK# during the
following clock (clock period 2 of Figure 6) are thereaf-
ter considered “locked.” A target, once locked,
requires that subsequent accesses to it deassert
LOCK# while FRAME# is asserted. Figure 7 shows a
subsequent access to a locked target by the master
which locked it. Because LOCK# is owned by a single
master, only that master is able to deassert it at the
beginning of a transaction (assuming successful
access to the locked target). A locked target can only
be unlocked during the clock period following the last
data transfer of a transaction when the LOCK# signal
is deasserted.
An unlocked target ignores LOCK# when it observes
that LOCK# is already asserted during the first clock
period of a transaction. This allows other masters to
access other (unlocked) targets. If an access to a
locked target is attempted by a master other than the
one that locked it, the target responds with a retry
request, as shown in Figure 8.
The S5920 responds to and supports bus masters
which lock it as a target.
107
DS1596
AMCC Confidential and Proprietary
AMCC [ APPLIED MICRO CIRCUITS CORPORATION ]
