A29L800A Series
Command Definitions
Writing specific address and data commands or sequences into
the command register initiates device operations. The
Command Definitions table 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 the "AC Characteristics" section.
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. The Command Definitions
table shows the address and data requirements. This method is
an alternative to that shown in the Autoselect Codes (High
Voltage Method) table, which is intended for PROM
programmers and requires V
ID
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
and another read cycle at XX03h retrieves the continuation
code. A read cycle at address XX01h returns the device code. A
read cycle containing a sector address (SA) and the address
02h in returns 01h if that sector is protected, or 00h if it is
unprotected. Refer to the Sector Address tables for valid sector
addresses.
The system must write the reset command to exit the autoselect
mode and return to reading array data.
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" for more information on this mode.
The system must issue the reset command to re-enable the
device for reading array data if I/O
5
goes high, or while in the
autoselect mode. See the "Reset Command" section, next.
See also "Requirements for Reading Array Data" in the "Device
Bus Operations" section for more information. The Read
Operations table provides the read parameters, and Read
Operation Timings diagram shows the timing diagram.
Word/Byte Program Command Sequence
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 verify the programmed cell
margin. Table 5 shows the address and data requirements for
the byte program command sequence.
When the Embedded Program algorithm is complete, the device
then returns to reading array data and addresses are longer
latched. The system can determine the status of the program
operation by using I/O
7
, I/O
6
, or RY/
BY
. See “White Operation
Status” for information on these status bits.
Any commands written to the device during the Embedded
Program Algorithm are ignored. Note that a hardware reset
immediately terminates the programming operation. The Byte
Program command sequence should be reinitiated once the
device has reset 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 I/O5 to
“1”, or cause the
Data
Polling algorithm to indicate the
operation was successful. However, a succeeding read will
show that the data is still “0”. Only erase operations can convert
a “0” to a “1”.
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 I/O
5
goes high during a program or erase operation, writing
the reset command returns the device to reading array data
(also applies during Erase Suspend).
(June, 2005, Version 1.1)
10
AMIC Technology, Corp.
AMICC [ AMIC TECHNOLOGY ]
