HPC3130

PCI HOT PLUG CONTROLLER

SCPS029B – DECEMBER1998

21

POST OFFICE BOX 655303

IDLEREQ, IDLEGNT, FRAME, and IRDY pins are not connected in manual mode. In contrast, during automatic

connection, the HPC3130 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 HPC3130 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 auto sequencing 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 auto-connection sequencing modes, the autodisconnect sequence has only one mode of operation.

The steps in the auto-disconnect 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 HPC3130 asserts IDLEREQ.

4.

Once IDLEGNT is asserted and FRAME and IRDY are deasserted, the HPC3130 deasserts BUSON and

CLKON and asserts REQ64ON to isolate the slot from the PCI bus.

5.

The HPC3130 then drives PWRON/OFF low to power off the slot.