s29al008d Meet Spansion Inc., s29al008d Datasheet - Page 22

• Manufacturer Part Number: s29al008d
• Description: 8 Megabit 1 M X 8-bit/512 K X 16-bit Cmos 3.0 Volt-only Boot Sector Flash Memory
• Manufacturer: Meet Spansion Inc.

8.2
8.3
8.4
22
Reset Command
Autoselect Command Sequence
Word/Byte Program Command Sequence
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).
The autoselect command sequence allows the host system to access the manufacturer and devices codes,
and determine whether or not a sector is protected.
requirements. This method is an alternative to that shown in
PROM programmers and requires V
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 in word
mode (or 02h in byte mode) 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
The system must write the reset command to exit the autoselect mode and return to reading array data.
The system may program the device by word or byte, depending on the state of the BYTE# pin. Programming
is a four-bus-cycle operation. The program command sequence is initiated by writing two unlock write cycles,
followed by the program set-up command. The program address and data are written next, which in turn
initiate the Embedded Program algorithm. The system is not required to provide further controls or timings.
The device automatically provides internally generated program pulses and verifies the programmed cell
margin.
sequence.
When the Embedded Program algorithm is complete, the device then returns to reading array data and
addresses are no longer latched. The system can determine the status of the program operation by using
DQ7, DQ6, or RY/BY#. See
Any commands written to the device during the Embedded Program Algorithm are ignored. Note that a
hardware reset immediately terminates the programming operation. The program command sequence
should be reinitiated once the device resets to reading array data, to ensure data integrity.
Programming is allowed in any sequence and across sector boundaries. A bit cannot be programmed from
a 0 back to a 1. Attempting to do so may halt the operation and set DQ5 to 1, or cause the Data# Polling
algorithm to indicate the operation was successful. However, a succeeding read shows that the data is still 0.
Only erase operations can convert a 0 to a 1.
Table 8.1 on page 26
Table 7.2 on page 16
Write Operation Status on page 27
shows the address and data requirements for the byte program command
ID
on address bit A9.
S29AL008D
and
D a t a
Table 7.3 on page 17
Table 8.1 on page 26
S h e e t
Table 7.4 on page
for information on these status bits.
S29AL008D_00_A10 November 27, 2007
for valid sector addresses.
shows the address and data
18, which is intended for