
S5335 – PCI Bus Controller, 3.3V
Revision 5.01 – November 30, 2005
Data Sheet
AMCC Confidential and Proprietary
DS1657 95
Read accesses from the S5335 operation registers
(S5335 as a target) are shown in Figure 47. The
S5335 conditionally asserts STOP# in clock period 3 if
the initiator keeps FRAME# asserted during clock
period 2 with IRDY# asserted (indicating a burst is
being attempted). Wait states may be added by the ini-
tiator by not asserting the signal IRDY# during clock 3
and beyond. If FRAME# remains asserted, but IRDY#
is not asserted, the initiator is just adding wait states,
not necessarily attempting a burst.
There is only one condition where accesses to S5335
operation registers do not return TRDY# but do assert
STOP#. This is called a target-initiated termination or
target disconnect and occurs when a read attempt is
made to an empty S5335 FIFO. The assertion of
STOP# without the assertion of TRDY# indicates that
the initiator should retry the operation later.
When burst read transfers are attempted to the S5335
operation registers, STOP# is asserted during the first
data transfer to indicate to the initiator that no further
transfers (data phases) are possible. This is a target-
initiated termination where the target disconnects after
the first data transfer. Figure 48 shows the signal rela-
tionships during a burst read attempt to the S5335
operation registers.
Figure 47. Single Data Phase PCI Bus Read of S5335 Registers (S5335 as Target)
Figure 48. Burst PCI Bus Read Attempt to S5335 Registers (S5335 as Target)
FRAME #
AD[31:0]
C/BE[3:0]#
IRDY#
TRDY#
DEVSEL#
STOP#
ADDRESS
DATA
BYTE ENABLES
BUS
COMMAND
1
2
3
4 5
(I)
(I)
(I)
(T)
(T)
(T)
(I)
(T)
(I) = DRIVEN BY INITIATOR
(T) = DRIVEN BY TARGET
PCI CLOCK
FRAME #
AD[31:0]
C/BE[3:0]#
IRDY#
TRDY#
DEVSEL#
STOP#
ADDRESS
DATA
BYTE ENABLES (1)
1
2
3
4 5
(I)
(I)
(T
)
(T
)
(T
)
(T)
(I)
(I)
BE (2)
BUS COMMAND
(I) = DRIVEN BY INITIATOR
(T) = DRIVEN BY TARGET