IRCC datasheet(75/79 Pages) SMSC

номер детали	IRCC

подробное описание детали	INFRARED COMMUNICATIONS CONTROLLER

PDF	79 Pages

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производитель	SMSC [SMSC Corporation]

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Zero Wait State Support

nSRDY

nSRDY can be driven by the IrCC to indicate that

an access cycle shorter than the standard I/O

cycle can be executed.

NOTE: the names

nSRDY & nNOWS can be used interchangeably.

nSRDY is enabled by the No Wait bit in SCE

Configuration Register B. When No Wait is one,

nSRDY goes active following the trailing edge of

the ISA I/O command and inactive following the

rising edge (Figure 48). nSRDY is suppressed

during DMA & refresh cycles, i.e. when AEN is

active, or when IOCHRDY is inactive. Zero Wait

State support is only available when the SCE is

enabled.

The Interaction of nSRDY and IOCHRDY

nSRDY and IOCHRDY determine the three types

of ISA access cycles: no-wait-state cycle,

standard cycle, ready cycle (Table 32). NOTE:

An inactive IOCHRDY suppresses nSRDY.

Table 32 - nSRDY and IOCHRDY Interaction

nSRDY

IOCHRDY

DESCRIPTION

active

No-wait-state Cycle (shortest length)

inactive

active

Standard Cycle (mean length)

inactive

Ready Cycle (longest length)

AEN

I/Ox

nSRDY

No Wait

FIGURE 48 - nSRDY TIMING

IRCC датащи(PDF) 75 Page - SMSC Corporation