FLASH
AS8F128K32
Autoselect Command Sequence
COMMAND DEFINITIONS
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
Writing specific address and data commands or sequences
into the command register initiates device operations. The
Command Definitions table defines the valid register com-
mand 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 WEx\ or
CEx\, whichever happens later. All data is latched on the ris-
ing edge of WEx\ or CEx\, whichever happens first. Refer to
the appropriate timing diagrams in the “AC Characteristics”
section.
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.
Aread cycle at address XX00h or retrieves the
manu-
Reading Array Data
facturer code.Aread 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 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.
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.
The system must write the reset command to exit the
autoselect mode and return to reading array data.
Byte Program Command Sequence
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 pro-
gram 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 automati-
cally provides internally generated program pulses and verify
the programmed cell margin. The Command Definitions take
shows the address and data requirements for the byte program
command sequence.
Reset Command
Writing the reset command to the device resets the de-
vice 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. Once pro-
gramming 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 au-
toselect mode, the reset command must be written to return to
reading array data.
If I/O5* goes high during a program or erase operation,
writing the reset command returns the device to reading array
data.
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/O7or I/O6. See “Write Operation
Status” for information on these status bits.
Any commands written to the device during the Embed-
ded 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 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”.
*NOTE: applies to every 8th byte (i.e. I/O5, I/O13, I/O21, I/O29)
Micross Components reserves the right to change products or specifications without notice.
AS8F128K32
Rev. 2.8 01/10
6
MICROSS [ MICROSS COMPONENTS ]
