pi7c8154b Pericom Semiconductor Corporation, pi7c8154b Datasheet - Page 99

• Manufacturer Part Number: pi7c8154b
• Description: Asynchronous 2-port Pci Bridge
• Manufacturer: Pericom Semiconductor Corporation

06-0008
15
15.1
15.2
15.2.1
15.2.2
BRIDGE BEHAVIOR
A PCI cycle is initiated by asserting the FRAME# signal. In a bridge, there are a number of
possibilities. Those possibilities are summarized in the table below:
BRIDGE ACTIONS FOR VARIOUS CYCLE TYPES
ABNORMAL TERMINATION (INITIATED BY BRIDGE
MASTER)
MASTER ABORT
Master abort indicates that when PI7C8154B acts as a master and receives no response (i.e., no
target asserts DEVSEL# or S_DEVSEL#) from a target, the bridge deasserts FRAME# and then
de-asserts IRDY#.
PARITY AND ERROR REPORTING
Parity must be checked for all addresses and write data. Parity is defined on the P_PAR, P_PAR64,
S_PAR, and S_PAR64 signals. Parity should be even (i. e. an even number of‘1’s) across AD,
CBE, and PAR. Parity information on PAR is valid the cycle after AD and CBE are valid. For
reads, even parity must be generated using the initiators CBE signals combined with the read data.
Again, the PAR signal corresponds to read data from the previous data phase cycle.
Initiator
Master on Primary
Master on Primary
Master on Primary
Master on Secondary
Master on Secondary
Master on Secondary
Target
Target on Primary
Target on Secondary
Target not on Primary nor
Secondary Port
Target on the same
Secondary Port
Target on Primary or the
other Secondary Port
Target not on Primary nor
the other Secondary Port
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Response
PI7C8154B does not respond. It detects this
situation by decoding the address as well as
monitoring the P_DEVSEL# for other fast and
medium devices on the Primary Port.
PI7C8154B asserts P_DEVSEL#, terminates
the cycle normally if it is able to be posted,
otherwise return with a retry. It then passes the
cycle to the appropriate port. When the cycle is
complete on the target port, it will wait for the
initiator to repeat the same cycle and end with
normal termination.
PI7C8154B does not respond and the cycle will
terminate as master abort.
PI7C8154B does not respond.
PI7C8154B asserts S_DEVSEL#, terminates
the cycle normally if it is able to be posted,
otherwise returns with a retry. It then passes
the cycle to the appropriate port. When cycle is
complete on the target port, it will wait for the
initiator to repeat the same cycle and end with
normal termination.
PI7C8154B does not respond.
MARCH 2006 REVISION 1.12
ASYNCHRONOUS 2-PORT
PCI-to-PCI BRIDGE
PI7C8154B