HPC3130A
PCI HOT PLUG CONTROLLER
SCPS055 – NOVEMBER 1999
13
POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
Terminal Functions (Continued)
system interface
TERMINAL
NAME
NO.
120
NO.
128
NO.
144
I/O FUNCTION
FRAME 20 21 23 I
Frame. This input and the IRDY input indicate that the PCI bus is idle. When the HPC3130A
senses the PCI bus is idle after IDLEGNT
is low, a hot-plug slot can be connected to the PCI
bus. This input must be wired to a valid logic level if the bus idling procedure is not implemented.
IDLEGNT 19 20 22 I
Idle grant. This input indicates when the PCI bus is idled by the HOST-PCI bridge after a
request is made by IDLEREQ
. The protocol is identical to PCI request/grant. This input must be
wired to a valid logic level if the bus idling procedure is not implemented.
IDLEREQ 18 19 21 O
Idle request. This output is driven to request the HOST-PCI bridge to idle the PCI bus before
connecting a hot-plug slot. The protocol is identical to PCI request/grant. A pullup resistor must
be implemented on this terminal if the bus idling procedure is not implemented.
INTR 24 25 27 O
System interrupt. This output provides a system interrupt. The HPC3130A can be programmed
to assert this interrupt under various conditions, which may be serviced by the hot-plug service.
Furthermore, the event status/enable state is compliant with the
ACPI Specification
and, as a
result, supports ACPI control methods for switching the HPC3130A.
INTR 23 24 26 O
System interrupt. This open drain output provides a system interrupt. The HPC3130A can be
programmed to assert this interrupt under various conditions, which may be serviced by the
hot-plug. Furthermore, the event status/enable state is compliant with the
ACPI Specification
and, as a result, supports ACPI control methods for switching the HPC3130A.
IRDY 21 22 24 I
Initiator ready . This and the FRAME input indicate that the PCI bus is idle. When the HPC3130A
senses the PCI bus is idle after IDLEGNT
is low, a hot-plug slot may be connected to the PCI
bus. This input must be wired to a valid logic level if the bus idling procedure is not implemented.
PCLK 16 17 19 I
PCI clock input. These terminals provide the PCI clock to the HPC3130A, which uses it only for
activity indicator timing, IDLEREQ
/IDLEGNT protocol, and connection sequencing.
PRST 14 15 17 I
PCI reset. This signal provides the PCI reset to the HPC3130A. After a PCI reset, the
HPC3130A resides in a state where all slots are enabled, as in a non-hot-plug system. The
HPC3130A passes PCI resets from the host to all hot-plug slots.
SGNT 13 14 16 O
Secondary grant. This output provides a scheme to cascade a secondary HPC3130A device in
order to provide more than four slots. The SGNT
output from the primary HPC3130A is input to
the IDLEGNT
terminal for the secondary HPC3130A. After the secondary HPC3130A requests
the primary HPC3130A to idle the bus, the primary HPC3130A arbitrates for the bus using
IDLEREQ
. Once IDLEGNT is asserted, the primary HPC3130A asserts its SGNT output. This
indicates to the secondary HPC3130A device that it can connect to the bus.
SMODE 27 28 30 I
Serial bus mode. When this input is asserted high, the internal HPC3130A registers are
accessible through the serial bus interface; otherwise, they are accessed through the generic
parallel bus interface. This input selects the control bus interface.
SREQ 12 13 15 I
Secondary request. This input provides a scheme to cascade a second HPC3130A device in
order to provide more than four slots. The IDLEREQ
from the second HPC3130A device is
input to the SREQ
terminal of the primary HPC3130A. If the second HPC3130A device
arbitrates for the bus by asserting its IDLEREQ
output, this scheme causes the primary
HPC3130A to assert its IDLEREQ
. If cascading is not used, this input is pulled high.
SYSM66EN 25 26 28 I/O
PCI bus frequency indicator. This signal indicates the PCI clock frequency requirements of the
hot-plug slots, and must be tied to the system PCI bus M66EN signal. The output from this
terminal only changes state after a PCI reset and is only required in a 66-MHz system.