M29DW323DT, M29DW323DB
COMMAND INTERFACE
All Bus Write operations to the memory are inter-
preted by the Command Interface. Commands
consist of one or more sequential Bus Write oper-
ations. Failure to observe a valid sequence of Bus
Write operations will result in the memory return-
ing to Read mode. The long command sequences
are imposed to maximize data security.
The address used for the commands changes de-
pending on whether the memory is in 16-bit or 8-
bit mode. See either Table
or
6,
depending on
the configuration that is being used, for a summary
of the commands.
Read/Reset Command
The Read/Reset command returns the memory to
its Read mode. It also resets the errors in the Sta-
tus Register. Either one or three Bus Write opera-
tions can be used to issue the Read/Reset
command.
The Read/Reset command can be issued, be-
tween Bus Write cycles before the start of a pro-
gram or erase operation, to return the device to
read mode. If the Read/Reset command is issued
during the time-out of a Block erase operation then
the memory will take up to 10µs to abort. During
the abort period no valid data can be read from the
memory. The Read/Reset command will not abort
an Erase operation when issued while in Erase
Suspend.
Auto Select Command
The Auto Select command is used to read the
Manufacturer Code, the Device Code, the Block
Protection Status and the Extended Memory Block
Verify Code. It can be addressed to either Bank.
Three consecutive Bus Write operations are re-
quired to issue the Auto Select command. The fi-
nal Write cycle must be addressed to one of the
Banks. Once the Auto Select command is issued
Bus Read operations to the Bank where the com-
mand was issued output the Auto Select data. Bus
Read operations to the other Bank will output the
contents of the memory array. The memory re-
mains in Auto Select mode until a Read/Reset or
CFI Query command is issued.
In Auto Select mode the Manufacturer Code can
be read using a Bus Read operation with A0 = V
IL
and A1 = V
IL
and A19-A20 = Bank Address. The
other address bits may be set to either V
IL
or V
IH
.
The Device Code can be read using a Bus Read
operation with A0 = V
IH
and A1 = V
IL
and A19-A20
= Bank Address. The other address bits may be
set to either V
IL
or V
IH
.
The Block Protection Status of each block can be
read using a Bus Read operation with A0 = V
IL
,
A1 = V
IH
, A19-A20 = Bank Address and A12-A18
specifying the address of the block inside the
Bank. The other address bits may be set to either
V
IL
or V
IH
. If the addressed block is protected then
01h is output on Data Inputs/Outputs DQ0-DQ7,
otherwise 00h is output.
Read CFI Query Command
The Read CFI Query Command is used to read
data from the Common Flash Interface (CFI)
Memory Area. This command is valid when the de-
vice is in the Read Array mode, or when the device
is in Auto Select mode.
One Bus Write cycle is required to issue the Read
CFI Query Command. Once the command is is-
sued subsequent Bus Read operations read from
the Common Flash Interface Memory Area.
The Read/Reset command must be issued to re-
turn the device to the previous mode (the Read Ar-
ray mode or Auto Select mode). A second Read/
Reset command would be needed if the device is
to be put in the Read Array mode from Auto Select
mode.
See
Tables
and
for details on the information contained in the
Common Flash Interface (CFI) memory area.
Program Command
The Program command can be used to program a
value to one address in the memory array at a
time. The command requires four Bus Write oper-
ations, the final write operation latches the ad-
dress and data, and starts the Program/Erase
Controller.
If the address falls in a protected block then the
Program command is ignored, the data remains
unchanged. The Status Register is never read and
no error condition is given.
During the program operation the memory will ig-
nore all commands. It is not possible to issue any
command to abort or pause the operation. After
programming has started, Bus Read operations in
the Bank being programmed output the Status
Register content, while Bus Read operations to
the other Bank output the contents of the memory
array. See the section on the Status Register for
more details. Typical program times are given in
After the program operation has completed the
memory will return to the Read mode, unless an
error has occurred. When an error occurs Bus
Read operations to the Bank where the command
was issued will continue to output the Status Reg-
ister. A Read/Reset command must be issued to
reset the error condition and return to Read mode.
Note that the Program command cannot change a
bit set at ’0’ back to ’1’. One of the Erase Com-
mands must be used to set all the bits in a block or
in the whole memory from ’0’ to ’1’.
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NUMONYX [ NUMONYX B.V ]
