
S5335 – PCI Bus Controller, 3.3V
Revision 5.01 – November 30, 2005
Data Sheet
AMCC Confidential and Proprietary
DS1657 100
Target Disconnects
There are many situations where a target may discon-
nect. Slow responding targets may disconnect to
permit more efficient (faster) devices to be accessed
while they prepare for the next data phase, or a target
may disconnect if it recognizes that the next data
phase in a burst transfer is out of its address range. A
target disconnects by asserting STOP#, TRDY#, and
DEVSEL# as shown in Figures 55 and 56. The initiator
in Figure 55 responds to the disconnect condition by
deasserting FRAME# on the following clock but does
not complete the data transfer until IRDY# is asserted.
This situation can only occur when the S5335 is a tar-
get. When the S5335 is an initiator, IRDY# is always
asserted during the data phase (no initiator wait
states). The timing diagram in Figure 56 applies to the
S5335 as either a target disconnecting or an initiator
with its target performing a disconnect. The S5335
performs a target disconnect if a burst access is
attempted to the PCI Operation Registers.
Figure 55. Target Disconnect Example 1 (IRDY# deasserted)
Figure 56. Target Disconnect Example 2 (IRDY# asserted)
PCI CLOCK
FRAME #
IRDY#
TRDY#
STOP#
DEVSEL#
1
2
3
DATA
TRANSFERRED
TARGET DISCONNECT
IDENTIFIED
(T)
(T)
(T)
(I)
(I)
(I) = DRIVEN BY INITIATOR
(T) = DRIVEN BY TARGET
PCI CLOCK
FRAME #
IRDY#
TRDY#
STOP#
DEVSEL#
1
2
3
DATA
TRANSFERRED
TARGET DISCONNECT
SIGNALED, DATA TRANSFERRED
(T)
(T)
(T)
(I)
(I)
(I) = DRIVEN BY INITIATOR
(T) = DRIVEN BY TARGET