S29AS016J datasheet(31/60 Pages) SPANSION

31 / 60 page

February 1, 2012 S29AS016J_00_11

S29AS016J

Data

She e t

10. Command Definitions

Writing specific address and data commands or sequences into the command register initiates device

operations. Table 11.1 on page 36 defines the valid register command sequences. Writing incorrect

address and data values or writing them in the improper sequence resets the device to reading array data.

All addresses are latched on the falling edge of WE# or CE#, whichever happens later. All data is latched on

the rising edge of WE# or CE#, whichever happens first. Refer to the appropriate timing diagrams in AC

Characteristics on page 46.

10.1

Reading Array Data

The device is automatically set to reading array data after device power-up. No commands are required to

retrieve data. The device is also ready to read array data after completing an Embedded Program or

Embedded Erase algorithm.

After the device accepts an Erase Suspend command, the device enters the Erase Suspend mode. The

system can read array data using the standard read timings, except that if it reads at an address within erase-

suspended sectors, the device outputs status data. After completing a programming operation in the Erase

Suspend mode, the system may once again read array data with the same exception. See Erase Suspend/

Erase Resume Commands on page 34 for more information on this mode.

The system must issue the reset command to re-enable the device for reading array data if DQ5 goes high, or

while in the autoselect mode. See Reset Command on page 31.

See also Requirements for Reading Array Data on page 15 for more information. The Read Operations

on page 46 provides the read parameters, and Figure 18.1 on page 46 shows the timing diagram.

10.2

Reset Command

Writing the reset command to the device resets the device to reading array data. Address bits are don’t care

for this command.

The reset command may be written between the sequence cycles in an erase command sequence before

erasing begins. This resets the device to reading array data. Once erasure begins, however, the device

ignores reset commands until the operation is complete.

The reset command may be written between the sequence cycles in a program command sequence before

programming begins. This resets the device to reading array data (also applies to programming in Erase

Suspend mode). Once programming begins, however, the device ignores reset commands until the operation

is complete.

The reset command may be written between the sequence cycles in an autoselect command sequence.

Once in the autoselect mode, the reset command must be written to return to reading array data (also applies

to autoselect during Erase Suspend).

If DQ5 goes high during a program or erase operation, writing the reset command returns the device to

reading array data (also applies during Erase Suspend).

10.3

Autoselect Command Sequence

The autoselect command sequence allows the host system to access the manufacturer and devices codes,

and determine whether or not a sector is protected. Table 11.1 on page 36 shows the address and data

requirements. This method is an alternative to that shown in Table 7.2 on page 18, which is intended for

PROM programmers and requires VID on address bit A9.

The autoselect command sequence is initiated by writing two unlock cycles, followed by the autoselect

command. The device then enters the autoselect mode, and the system may read at any address any

number of times, without initiating another command sequence.

A read cycle at address XX00h retrieves the manufacturer code. A read cycle at address XX01h returns the

device code. A read cycle containing a sector address (SA) and the address 02h in word mode (or 04h in byte

mode) returns 01h if that sector is protected, or 00h if it is unprotected. Refer to Table 7.3 on page 19 and

Table 7.4 on page 20 for valid sector addresses.

The system must write the reset command to exit the autoselect mode and return to reading array data.

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