HPC3130A
PCI HOT PLUG CONTROLLER
SCPS055 – NOVEMBER 1999
connection sequencing (continued)
PCI_CLK
PWRON/OFF
PWRGOOD
SLOTRST
CLKON
REQ64ON
SLOTREQ64
BUS_CTL
IDLEREQ
IDLEGNT
FRAME
IRDY
BUSON
Figure 8. Automatic Connection Sequencing Mode 2
The protocol described above is identical to the PCI REQ/GNT protocol used by PCI bus masters, which also
must wait for bus idle through PCI FRAME and IRDY before initiating a PCI cycle. If the HPC3130A is connected
to PCI FRAME and IRDY, the HPC3130A arbitrates for the bus; although it does not drive the PCI bus or assert
FRAME to start a cycle.
There are some issues with this implementation such as bus parking and additional loading on the PCI FRAME
and IRDY signals, which need to be considered when designing a system. The system designer may have a
level of confidence that PCI adapter cards can tolerate connection to a non-idle bus. In the scenario where the
HPC3130Aisnotconnectedtothebus, thentheFRAME, IRDY, andIDLEGNTmustbewiredtovalidlogiclevels
and the automatic sequencing will start without any relationship to the bus.
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