PC48F4400PLVB0 datasheet(81/102 Pages) NUMONYX

81 / 102 page

November 2007

Datasheet

Order Number: 290701-18

Numonyx™ Wireless Flash Memory (W18)

14.3

WAIT Signal Polarity (RCR[10])

If the WAIT bit is cleared (RCR[10]=0), then WAIT is configured to be asserted low.

This means that a 0 on the WAIT signal indicates that data is not ready and the data

bus contains invalid data. Conversely, if RCR[10] is set, then WAIT is asserted high. In

either case, if WAIT is deasserted, then data is ready and valid. WAIT is asserted during

asynchronous page mode reads.

14.4

WAIT Signal Function

The WAIT signal indicates data valid when the device is operating in synchronous mode

(RCR[15]=0), and when addressing a partition that is currently in read-array mode.

The WAIT signal is only “deasserted” when data is valid on the bus.

When the device is operating in synchronous non-read-array mode, such as read

status, read ID, or read query, WAIT is set to an “asserted” state as determined by

RCR[10]. See Figure 12, “WAIT Signal in Synchronous Non-Read Array Operation

Waveform” on page 35.

When the device is operating in asynchronous page mode or asynchronous single word

read mode, WAIT is set to an “asserted” state as determined by RCR[10]. See Figure 8,

“Page-Mode Read Operation Waveform” on page 31, and Figure 6, “Asynchronous Read

Operation Waveform” on page 29.

From a system perspective, the WAIT signal is in the asserted state (based on

RCR[10]) when the device is operating in synchronous non-read-array mode (such as

Read ID, Read Query, or Read Status), or if the device is operating in asynchronous

mode (RCR[15]=1). In these cases, the system software should ignore (mask) the

WAIT signal, because it does not convey any useful information about the validity of

what is appearing on the data bus.

Figure 38: Example: Latency Count Setting at 3

MAX-0 (A)

15-0 (D/Q)

CLK (C)

CE# (E)

ADV# (V)

R103

Valid

Output

Valid

Output

High Z

ADD-DELAY

DATA

1nd

0st

2rd

3th

4th

Valid Address

Code 3

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