PCI1221 datasheet(34/123 Pages) TI

34 / 123 page

PCI1221 GHK/PDV

PC CARD CONTROLLERS

SCPS042 – JULY 1998

POST OFFICE BOX 655303

• DALLAS, TEXAS 75265

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 PCI1221. The PCI1221 provides several interrupt signaling schemes to accommodate the needs of a variety

of platforms. The different mechanisms for dealing with interrupts in this device 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 PCI1221 is, therefore, backward compatible with existing interrupt control register definitions, and new

registers have been defined where required.

The PCI1221 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 PCI1221, PC

Card interrupts are classified as either card status change (CSC) or as functional interrupts.

The method by which any type of PCI1221 interrupt is communicated to the host interrupt controller varies from

system to system. The PCI1221 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 signalling is provided through the seven multifunction terminals,

MFUNC0–6.

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 PCI1221 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 10 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 three types

of cards that can be inserted into any PC Card socket are:

D 16-bit memory card

D 16-bit I/O card

D CardBus cards

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