HPC3130A
PCI HOT PLUG CONTROLLER
SCPS055 – NOVEMBER 1999
66-MHz PCI support
The HPC3130A supports up to two slots in a 66-MHz system: slot 0 and slot 1. These hot-plug slot interfaces
include the M66EN signal and the SYSM66EN signal communicates hot-plug slot capability to the system.
Figure 14 illustrates the 66-MHz support function in the HPC3130A.
HPC–PCI M66EN FUNCTION
M66EN_0
M66EN_I
P
C
CO
CLKON 0
PRST
CB1G1257
SYSM66EN
PCI
SLOT
System PCI Bus
33 MHz
66 MHz
Motherboard
PCI Device
PCLK DRIVER
Figure 14. HPC3130A 66-MHz System Support
When the PCIRST signal is deasserted, the SYSM66EN signal is latched and selects the system frequency.
Before an adapter card can be inserted, the slot is prepared for insertion by deasserting BUSON, deasserting
CLKON, and powering down the slot. When an adapter card is inserted into either hot-plug slot 0 or slot 1,
PWRON/OFF is high, and power is applied, the value M66EN from the card can be read through internal
registers. If the bus is operating at 66-MHz and a 33-MHz adapter card is inserted, then the software ensures
that the card is never connected to the bus. If the bus is operating at 33 MHz and a 66-MHz adapter card is
inserted, then the latched SYSM66EN state can be driven to the slot by enabling the CBT switch using CLKON.
SYSM66EN and CLKON input to a clock driver circuit to control the PCI clock frequency. The 66-MHz support
designed into the HPC3130A allows option cards to indicate PCI clock frequency capabilities upon PCI reset;
however, does not allow an inserted hot-plug card to alter the clock frequency of an operating PCI bus.
24
POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
TI [ TEXAS INSTRUMENTS ]
