PCI6621 datasheet(63/204 Pages) TI

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3−15

3.7

Programmable Interrupt Subsystem

Interrupts provide a way for I/O devices to let the microprocessor know that they require servicing. The dynamic

nature of PC Cards and the abundance of PC Card I/O applications require substantial interrupt support from the

PCI6x21/PCI6x11 controller. The PCI6x21/PCI6x11 controller provides several interrupt signaling schemes to

accommodate the needs of a variety of platforms. The different mechanisms for dealing with interrupts in this

controller are based on various specifications and industry standards. The ExCA register set provides interrupt

control for some 16-bit PC Card functions, and the CardBus socket register set provides interrupt control for the

CardBus PC Card functions. The PCI6x21/PCI6x11 controller is, therefore, backward compatible with existing

interrupt control register definitions, and new registers have been defined where required.

The PCI6x21/PCI6x11 controller detects PC Card interrupts and events at the PC Card interface and notifies the host

controller using one of several interrupt signaling protocols. To simplify the discussion of interrupts in the

PCI6x21/PCI6x11 controller, PC Card interrupts are classified either as card status change (CSC) or as functional

interrupts.

The method by which any type of PCI6x21/PCI6x11 interrupt is communicated to the host interrupt controller varies

from system to system. The PCI6x21/PCI6x11 controller offers system designers the choice of using parallel PCI

interrupt signaling, parallel ISA-type IRQ interrupt signaling, or the IRQSER serialized ISA and/or PCI interrupt

protocol. It is possible to use the parallel PCI interrupts in combination with either parallel IRQs or serialized IRQs,

as detailed in the sections that follow. All interrupt signaling is provided through the seven multifunction terminals,

MFUNC0−MFUNC6.

3.7.1

PC Card Functional and Card Status Change Interrupts

PC Card functional interrupts are defined as requests from a PC Card application for interrupt service and are

indicated by asserting specially-defined signals on the PC Card interface. Functional interrupts are generated by

16-bit I/O PC Cards and by CardBus PC Cards.

Card status change (CSC)-type interrupts are defined as events at the PC Card interface that are detected by the

PCI6x21/PCI6x11 controller and may warrant notification of host card and socket services software for service. CSC

events include both card insertion and removal from PC Card sockets, as well as transitions of certain PC Card

signals.

Table 3−9 summarizes the sources of PC Card interrupts and the type of card associated with them. CSC and

functional interrupt sources are dependent on the type of card inserted in the PC Card socket. The four types of cards

that can be inserted into any PC Card socket are:

•

16-bit memory card

•

16-bit I/O card

•

CardBus cards

•

UltraMedia card

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