S29AS016J datasheet(27/59 Pages) CYPRESS

27 / 59 page

Document Number: 002-01122 Rev.*L

Page 27 of 59

S29AS016J

10. Command Definitions

Writing specific address and data commands or sequences into the command register initiates device operations. Table on page 32

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 44.

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 30 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 27.

See also Requirements for Reading Array Data on page 11 for more information. The Read Operations on page 44 provides the

read parameters, and Figure 18.1 on page 44 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 on page 32 shows the address and data requirements. This method is an alternative to that

shown in Table on page 13, 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 on page 13 and Table on page 15 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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