A29001/A290011 Series
Command Definitions
Autoselect Command Sequence
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.
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
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 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.
All addresses are latched on the falling edge of
or
WE
, whichever happens later. All data is latched on the
CE
rising edge of
or
, whichever happens first. Refer
WE
CE
to the appropriate timing diagrams in the "AC
Characteristics" section.
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
The system must write the reset command to exit the
autoselect mode and return to reading array data.
Byte Program Command Sequence
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/O5 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.
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.
The Command Definitions table 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 no longer latched. The system can determine the
status of the program operation by using I/O7 or I/O6. See
"Write Operation Status" for information on these status
bits.
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).
Any commands written to the device during the Embedded
Program Algorithm are ignored. 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
Polling algorithm to indicate the operation was
Data
successful. However, a succeeding read will show that the
data is still "0". Only erase operations can convert a "0" to
a "1".
If I/O5 goes high during a program or erase operation,
writing the reset command returns the device to reading
array data (also applies during Erase Suspend).
(December, 2004, Version 1.3)
8
AMIC Technology, Corp.
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