82870P2P64H2 Datasheet, PDF (135/217 Pages) –

Functional Description
R
4.3
4.3.1
4.3.1.1
Hot Plug Controllers
The P64H2 hot plug controller allows PCI card removal, replacement, and addition without
powering down the system. In this section the standard specification signal names are used for the
hot plug signal names and PCI signal names. For actual P64H2 signal names, the letters “A” and
“B” are used in the signal names to distinguish between PCI Interface A and PCI Interface B.
System Architecture
The P64H2 hot plug controller resides in Function 0 of the secondary bus device 31. It supports
three to six PCI slots through an input/output serial interface when operating in Serial Mode, and 1
to 2 slots through an input/output parallel interface when operating in Parallel Mode. The input
serial interface is polling and is in continuous operation. The output serial interface is “demand”
and acts only when requested. These serial interfaces run at about 8.25 MHz regardless of the
speed of the PCI bus. In parallel mode, the P64H2 performs the serial to parallel conversion
internally, so the serial interface cannot be observed. However, internally the hot plug controller
always operates in a serial mode.
Output Control
The output interface is responsible for driving seven bits per slot (plus 8 general purpose output
bits in serial mode).
• POWER ENABLE: Connected to an analog component designed to regulate current and
voltage of the slot, and generates a (power) fault signal when an abnormal condition is
detected.
• CLOCK ENABLE#, BUS ENABLE#: Connects the PCI bus and clock signal of the slot to
the system bus PCI bus via FET isolation switches.
• RESET#: Connected to the PCIRST# pin of the slot.
• AMBER and GREEN LEDs: Connected to LEDs on the chassis to indicate a slot’s status to
the user.
• General Purpose Outputs: (only in Serial Mode)
The general-purpose output bits are set using bits 0 through 7 of the General Purpose Output
Register (Offset 13h) in memory space. The other output bits are set by the hot plug controller
based on the Slot Power Enable Register (Offset 2Dh) and the Slot Enable Register (Offset 01h) in
memory space.
In a well-behaved environment, the output sequences are initiated by software. However, the hot
plug controller can act without software intervention to disable power to a slot and turn off its
LEDs, if a PCI card is being removed from a powered PCI slot.
Intel^® 82870P2 P64H2 Datasheet
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