PPC34C60 datasheet(43/58 Pages) SMSC

43 / 58 page

SMSC DS – PPC34C60

Page 43

Rev. 06/01/2001

ADVANCED INFORMATION

SPP NIBBLE READ (PARALLEL PORT SIGNALS)

PARAMETER

MIN

TYP

MAX

UNITS

The PPC34C60 assembles a nibble of data and places it

on the status lines. The PPC34C60 then deasserts the

BSY signal to inform the Host that a valid nibble is

available.

[SCLK]

Once the Host senses that the BSY line is deasserted it

will then internally latch the nibble and then assert nSTB to

tell the PPC34C60 to get the next nibble.

It will take the PPC34C60 this amount of time to fetch and

present the next nibble of data.

250

[6 SCLK]

nSTB asserted pulse width

125

[3 SCLK]

nSTB deasserted pulse width

125

[3 SCLK]

Once the PPC34C60 has placed the next nibble, this is the

time for the Host to latch the nibble and then assert nSTB

to tell the PPC34C60 to get the next nibble.

[SCLK]

Once the Host has latched the last nibble it asserts the

nSTB signal to inform the PPC34C60 to fetch another

more data. If the PPC34C60 has to perform a DRAM or

BUS cycle it may have to assert the BSY signal until it has

completed the cycle and has placed a valid nibble on the

status lines.

This time represents the time from the

assertion of nSTB to the assertion of BSY when

appropriate.

334

[8 SCLK]

375

[9 SCLK]

This time represents the time it takes the PPC34C60 to

fetch and present the next valid nibble on the status lines.

This time will vary significantly based on the type of access

and the BCLK currently selected. These values are based

on BCLK = 2 SCLK.

1,084

[13 BCLK]

PPC34C60 数据表(PDF) 43 Page - SMSC Corporation

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