HPC3130A
PCI HOT PLUG CONTROLLER
SCPS055 – NOVEMBER 1999
connection sequencing (continued)
IDLEREQ, IDLEGNT, FRAME, and IRDY pins are not connected in manual mode. In contrast, during automatic
connection, the HPC3130A requests the PCIBus to make sure it is idle before it sequences through the
connection sequence.
In manual mode, software has to perform each part of the connection sequence. Figure 9 is an example of the
manual connection sequence. There could be several other ways to implement this protocol.
PCI_CLK
PWRON/OFF
PWRGOOD
SLOTRST
CLKON
REQ64ON
SLOTREQ64
BUS_CTL
BUSON
Figure 9. Manual Connection Sequencing
disconnecting sequence
The HPC3130A provides two mechanisms to isolate a PCI slot from the PCI bus so an add–in card can be
removed. One of the mechanisms is called manual sequencing and is enabled by default. This mechanism
allows the software to control the entire disconnect sequence. This means it is the software’s responsibility to
remove a powered slot from the PCI bus without any impact to the system.
The second mechanism is called autosequencing and can be enabled by programming either Auto-Sequence
1 or Auto-Sequence 2 in the general configuration register. Unlike the connection sequence, which has two
different autoconnection sequencing modes, the autodisconnect sequence has only one mode of operation.
The steps in the autodisconnect sequence are as follows:
1. Software may assert SLOTRST to the appropriate slot by writing a 0 to the SLOTRST_O bit in the hot-plug
control register. This is optional.
2. Next the software must set the BUS_CTL bit in the hot-plug control register to a 1.
3. Once the BUS_CTL bit is set to a 1, the HPC3130A asserts IDLEREQ.
4. Once IDLEGNT is asserted and FRAME and IRDY are deasserted, the HPC3130A deasserts BUSON and
CLKON and asserts REQ64ON to isolate the slot from the PCI bus.
5. The HPC3130A then drives PWRON/OFF low to power off the slot.
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